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Update prom-specific documentation
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Tom Nisbet
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@ -4,10 +4,28 @@ permalink: /docs/prom-specific-code
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exerpt: "PROM types supported by TommyPROM - EPROM, EEPROM, Flash"
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---
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TommyPROM can be used to read and write several different types of PROM chips. Due to
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differences in the technologies of these chips, some features of TommyPROM may work
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differently or may not be applicable at all. The standard code can read most types of
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PROM, even if there is no specific software support for them.
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TommyPROM can be used to read and write many different types of EEPROM, Flash, and EPROM
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chips. Due to differences in the technologies of these chips, some features of TommyPROM
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may work differently or may not be applicable at all. The standard code can read most
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types of PROM, even if there is no specific software support for them.
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Broadly speaking, there are two different ways to write to chips. The first method is
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similar to a static RAM - the WE signal is asserted and data is written to a location
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using the data and address lines. This is the case for the 28C64. Some of these chips,
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like the 27C257, need a programming voltage to be present on the Vpp or PGM pin. There
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are usually timing requirements for the program pulse and there may be repeated write
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cycles needed with a verification cycle to complete the write.
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The second method is the use of a program command register. Bytes are written to a single
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location by sending a command string, which is a series of chip writes. These chips
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usually have additional commands to erase sectors or to lock and unlock the chip. The
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SST39SF010 is an example of a chip that uses a command register.
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Some chips use a combination of both methods. The 28C256 uses a command register to
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enable and disable Software Data Protection, but uses a direct write for programming.
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TommyPROM has a variety of PromDevice Modules that can be compiled in to support these
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different chip technologies.
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# Verified Chips
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@ -100,46 +118,9 @@ The 8755 build of TommyPROM also has a circuit to control the 25V programming pu
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# Misc Flash
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# Chip Details
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#### 29C Series
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The 29C series flash chips are similar to the 28C EEPROMs, except they must erase an
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entire sector before programming new data. The start of a block write operation causes
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the target sector to be erased before the block is written. If the entire sector is not
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written in one operation, there is no way to write additional data to the sector because
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a new block write will erase the sector again.
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The write algorithm for the 29C chips is similar to 28C, so it is possible to use that
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code to write these chips as well with some restrictions. All 29C010 and 29C020 chips
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that have been encountered use a sector size of either 64 bytes or 128 bytes. A single
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XModem packet holds 128 bytes of data, so these chips will program without issue.
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The 28C040 chips from some manufacturers use a 256 byte sector. This will not currently
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work with TommyPROM, because each of the 128 byte XModem packets received will do its own
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block write. The first write will erase 256 bytes and then write data into the first half
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of the sector. The second write will then erase the data just written and then write 128
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bytes into the second half of the sector. To fix this, the code would need to be modified
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to keep 256 bytes of data from two packets before initiating a block write.
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#### 28F Series
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The 28F series flash do not have sectors. The entire chip must be erased before writing
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new data. Data is written a byte at a time using a command register to control the
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programming. **These chips require a 12V programming voltage that must be present during
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the programming or erase operations**. TommyPROM does not currently support 28F chips,
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but it would not be difficult to write a driver. The default 28C driver will read 28F
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chips.
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#### 29F Series
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The 29F series flash have sectors that must be explicitly erased before writing new
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data. Data is written a byte at a time using a command register to control the
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programming. TommyPROM does not currently support 29F chips, but it would not be
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difficult to write a driver. The default 28C driver will read 29F chips.
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#### 28C256
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## 28C Series 28C256
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Tested with chips from several manufacturers including Atmel AT28C256, Xicor X28C256, and
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CSI CAT28C256. Also works with the smaller 28C64 and 28C16 chips, although some
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@ -153,7 +134,7 @@ The 28C chips do not need to be explicitly erased. Each memory cell is automati
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erased during a write operation, so they are more similar to a slow RAM than to other
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PROMs.
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#### SST39SF040
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## SST39SF040
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The SST39SF driver supports all chips in this family, so the 040, 020, and 010 chips can
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be all be used with no code change. These chips use sectors that must be erased before
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@ -161,14 +142,53 @@ writing new data. The code keeps track of the current sector and will automatic
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an erase operation whenever a write starts to a new sector. The _Erase_ command is
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supported, but is not needed unless overwriting new data to a single sector.
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#### SST28SF040
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## SST28SF040
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This is an earlier version of the SST39SF series chips. They are pin compatible with the
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39SF series, but use a different command set for programming. Unlike the 39SF, these
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flash chips support software data protection. The _Lock_ and _Unlock_ commands can be
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used to enable and disable SDP from the command line.
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#### SST27SF020
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## 29C Series
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The 29C0x0 chips are 5V sectored flash chips. They are similar to the 28C EEPROMs,
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except they must erase an entire sector before programming new data. The start of a block
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write operation causes the target sector to be automatically erased before the block is
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written. If the entire sector is not written in one operation, there is no way to write
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additional data to the sector because a new block write will erase the sector again.
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The write algorithm for the 29C chips is similar to 28C, so it is possible to use that
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code to write these chips as well with some restrictions.
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All 29C010 and 29C020 chips that have been encountered use a sector size of either 64
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bytes or 128 bytes. A single XModem packet holds 128 bytes of data, so these chips will
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program without issue.
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The 28C040 chips from some manufacturers use a 256 byte sector. *This will not currently
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work with TommyPROM*, because each of the 128 byte XModem packets received will do its own
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block write. The first write will erase 256 bytes and then write data into the first half
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of the sector. The second write will then erase the data just written and then write 128
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bytes into the second half of the sector. To fix this, the code would need to be modified
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to keep 256 bytes of data from two packets before initiating a block write.
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## 28F Series
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The 28F series flash do not have sectors. The entire chip must be erased before writing
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new data. Data is written a byte at a time using a command register to control the
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programming. **These chips require a 12V programming voltage that must be present during
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the programming or erase operations**. TommyPROM does not currently support 28F chips,
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but it would not be difficult to write a driver. The default 28C driver will read 28F
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chips.
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## 29F Series
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The 29F series flash have sectors that must be explicitly erased before writing new
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data. Data is written a byte at a time using a command register to control the
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programming. TommyPROM does not currently support 29F chips, but it would not be
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difficult to write a driver. The default 28C driver will read 29F chips.
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## SST27SF020
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The Silicon Storage SST27SF0x0 are programmed similarly to the 27C257 in that a constant
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voltage is applied for program and erase operations. Unlike the 27C257, these have a
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@ -180,6 +200,8 @@ the newer 28C EEPROMs, these chips do not automatically erase before writing to
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location. Instead, the entire chip is erased by applying 12V to _VPP_ and _A9_ and then
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pulsing _WE_.
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## 27C and 27E Series EPROMs and flash
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#### W27C257 and W27C512
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The Winbond W27C257 and W27E257 appear to be identical 32Kx8 EEPROMs. The 27C version
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@ -204,16 +226,6 @@ Note that the W27x257 chip are almost a drop-in replacement for the 28C256. The
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_VPP_, and _A14_ pins are the only differences. For reading, the _VPP_ pin should be
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connected to 5V.
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#### 29C010
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The 29C0x0 chips are 5V sectored flash chips. They automatically erase a sector at the
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start of a new write, so they can be used with the default 28C code.
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Note that some versions of the 29C040 use a 256 byte sector size. This will not work
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with the TommyPROM code because the XModem transfer buffer is only 128 bytes. Code
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changes would be needed to buffer up two packets of data into a single write operation
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for chips with the 256 byte buffer.
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# Chips to be Tested
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|Model |Manufacturer |Type |Module |Notes|
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@ -4,14 +4,6 @@ permalink: /docs/prom-families
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exerpt: "PROM types supported by TommyPROM - EPROM, EEPROM, Flash"
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---
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TommyPROM can be used to read and write several different types of PROM chips. Due to
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differences in the technologies of these chips, some features of TommyPROM may work
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differently or may not be applicable at all. The standard code can read most types of
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PROM, even if there is no specific software support for them.
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# PROM Types
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## EPROM - Erasable Programmable Read-only Memory
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EPROMs can be written once, but must then be erased by exposing them to UV light for
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@ -20,12 +12,15 @@ support for programming.
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## EEPROM - Electrically Erasable Programmable Read-only Memory
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EEPROMs are the easiest PROMs to use. Modern EEPROMs usually can be erased and reprogrammed
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electrically at the individual byte level. This makes them appear similar to a slower
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static RAM. All of the interactive features of TommyPROM work well with EEPROMs. Due
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to their complexity, EEPROMs typically come in smaller sizes than other technologies.
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The largest EEPROM in the 28C family is 32K bytes. Some older EEPROMs cannot be reprogrammed at the individual byte level and are instead bulk erased before a new write
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operation. Programming and erasing for these chips usually requires voltages higher than 5V.
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EEPROMs are the easiest PROMs to use. Modern EEPROMs usually can be erased and
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reprogrammed electrically at the individual byte level. This makes them appear similar to
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a slower static RAM. All of the interactive features of TommyPROM work well with EEPROMs.
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Due to their complexity, EEPROMs typically come in smaller sizes than other technologies.
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The largest EEPROM in the 28C family is 32K bytes.
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Some older EEPROMs cannot be reprogrammed at the individual byte level and are instead
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bulk erased before a new write operation. Programming and erasing for these chips usually
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requires voltages higher than 5V.
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## Flash ROM
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@ -41,192 +36,6 @@ do multiple writes to the same sector work differently.
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## OTP ROM - One-time Programmable ROM
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One-time Programmable (OTP) ROM is written once, either at the factory or in the field.
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These chips cannot be erased and re-written, but they can be read by TommyPROM. Interesting
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trivia - some of the field-programmable OTPs are just EPROMs packaged without the erase
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window.
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# Supported Chip Families
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## 28C EEPROM
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The 28C series EEPROMs, specifically the 28C256, are the original chips that TommyPROM
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supported. As a result, these have the best support, with all of the interactive features
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of the command line. In addition the basic read and write operations, there are also
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commands to enable and disable the [Software Data protection (SDP)](../28C256-notes)
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features of 28C chips. There is also support for the fast block write mode of these
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chips, allowing a 32KB chip to be programmed in just a few seconds.
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## 27C EPROM
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The 27C EPROMs use a variety of programming algorithms. Code exists for some of these,
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but very few of the chips have been tested.
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Most, if not all, 27C series chips are not 5V only and require a higher voltage to program
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them. Some need the voltage constantly applied while programming and others use high
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voltage pulses for each byte. For constant voltage chips, it is probably easiest to just
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add an external power supply and manually assert the voltage before starting a write. For
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those with switched voltages, some elements of the 8755 hardware may be leveraged to build
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a version of the programer that supports these chips.
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## Atmel SST39SF Flash
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TommyPROM has a driver for Atmel SST39SF NOR flash chips. This driver replaces the 28C
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driver at compile time. See configure.h to enable a different driver.
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The SST39SF chips use fixed 4KB sectors that must be manually erased before a new program
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operation, but the code manages this transparently. Whenever a write is started to a new
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segment, the driver first initiates an erase of that sector. A second write to the same
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sector will not cause an erase, so it is possible to write to a segment multiple times
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with no additional steps as long as the writes are to different parts of the sector. For
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example, 256 bytes could be written to the start of a sector from one file and then 512
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bytes could be written to the end of the sector from another file.
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Writing data that spans multiple sectors also works with no additional steps. When
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a sector boundary is crossed, the new sector is erased and set as the current sector.
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The SST39SF driver supports a manual erase from the command line using the E command.
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This is only needed if data will be rewritten to the same location after a previous write
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to that sector.
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There is also a driver for the SST28SF0x0 SuperFlash chips. These are an earlier version
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of the 39SF chips, using 256-byte sectors. The 28SF and 39SF chips are pin compatible,
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but use different command sets for programming and erasing. For read-only applications,
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they should be identical, although the 28SF are slower.
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All programming and erase operations for both the 39SF and 28SF chips require only a
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single 5V power supply.
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## Misc Flash
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#### 29C Series
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The 29C series flash chips are similar to the 28C EEPROMs, except they must erase an
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entire sector before programming new data. The start of a block write operation causes
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the target sector to be erased before the block is written. If the entire sector is not
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written in one operation, there is no way to write additional data to the sector because
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a new block write will erase the sector again.
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The write algorithm for the 29C chips is similar to 28C, so it is possible to use that
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code to write these chips as well with some restrictions. All 29C010 and 29C020 chips
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that have been encountered use a sector size of either 64 bytes or 128 bytes. A single
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XModem packet holds 128 bytes of data, so these chips will program without issue.
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The 28C040 chips from some manufacturers use a 256 byte sector. This will not currently
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work with TommyPROM, because each of the 128 byte XModem packets received will do its own
|
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block write. The first write will erase 256 bytes and then write data into the first half
|
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of the sector. The second write will then erase the data just written and then write 128
|
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bytes into the second half of the sector. To fix this, the code would need to be modified
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to keep 256 bytes of data from two packets before initiating a block write.
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#### 28F Series
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The 28F series flash do not have sectors. The entire chip must be erased before writing
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new data. Data is written a byte at a time using a command register to control the
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programming. **These chips require a 12V programming voltage that must be present during
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the programming or erase operations**. TommyPROM does not currently support 28F chips,
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but it would not be difficult to write a driver. The default 28C driver will read 28F
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chips.
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#### 29F Series
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The 29F series flash have sectors that must be explicitly erased before writing new
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data. Data is written a byte at a time using a command register to control the
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programming. TommyPROM does not currently support 29F chips, but it would not be
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difficult to write a driver. The default 28C driver will read 29F chips.
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## Intel 8755/8355 EPROM
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TommyPROM has a driver for Intel 8755 EPROMs. This driver replaces the 28C driver at
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compile time. See configure.h to enable a different driver. This driver will also read
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Intel 8355 OTP EPROMs. Also note that the TommyPROM hardware for the 8755 is drastically
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different from the other versions.
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The Intel 8755 is a peripheral chip designed for 8085 systems. It is a 40 pin device that
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contains a 2KB EPROM plus two general-purpose I/O ports. The 8355 is a one-time
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programmable version of the 8755. The 8755 requires a 25V programming pulse for each byte
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to be written.
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A new hardware build was created to support the 8755 chips. Because the 8755 has a multiplexed data and address bus, the usual shift registers are not used for addressing.
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The chip only needs 8 connects that are shared for address and data, plus three dedicated
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address lines. The Arduino has enough pins to drive all of these directly, without the
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need for shift registers to create address lines.
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The 8755 build of TommyPROM also has a circuit to control the 25V programming pulses.
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# Chips
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#### 28C256
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Tested with chips from several manufacturers including Atmel AT28C256, Xicor X28C256, and
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CSI CAT28C256. Also works with the smaller 28C64 and 28C16 chips, although some
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parameters may need to be adjusted. Some smaller chips do not support SDP, so the _Lock_
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and _Unlock_ commands have no effect. Check the datasheet to see if block writes are
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supported. Some 28C16s use a 16 byte block instead of the 64 bytes used on the 28C256.
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It is always safe to just set the block size parameter to zero when declaring the chip to
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disable block writes altogether.
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The 28C chips do not need to be explicitly erased. Each memory cell is automatically
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erased during a write operation, so they are more similar to a slow RAM than to other
|
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PROMs.
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|
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#### SST39SF040
|
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The SST39SF driver supports all chips in this family, so the 040, 020, and 010 chips can
|
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be all be used with no code change. These chips use sectors that must be erased before
|
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writing new data. The code keeps track of the current sector and will automatically do
|
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an erase operation whenever a write starts to a new sector. The _Erase_ command is
|
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supported, but is not needed unless overwriting new data to a single sector.
|
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|
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#### SST28SF040
|
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This is an earlier version of the SST39SF series chips. They are pin compatible with the
|
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39SF series, but use a different command set for programming. Unlike the 39SF, these
|
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flash chips support software data protection. The _Lock_ and _Unlock_ commands can be
|
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used to enable and disable SDP from the command line.
|
||||
|
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#### SST27SF020
|
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|
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The Silicon Storage SST27SF0x0 are programmed similarly to the 27C257 in that a constant
|
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voltage is applied for program and erase operations. Unlike the 27C257, these have a
|
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dedicated WE pin that controls programming and erasing. Another difference is that they
|
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do not have a verify operation to read back the programmed data.
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These Flash chips have a _VPP_ pin that needs a constant 12V during programming. Unlike
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the newer 28C EEPROMs, these chips do not automatically erase before writing to a
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location. Instead, the entire chip is erased by applying 12V to _VPP_ and _A9_ and then
|
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pulsing _WE_.
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#### W27C257 and W27C512
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The Winbond W27C257 and W27E257 appear to be identical 32Kx8 EEPROMs. The 27C version
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has been tested. The Winbond W27C512 is a 64Kx8 EEPROM with no dedicated _VPP_ pin.
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The 257 EEPROMs have a _VPP_ pin that needs a constant 12V during programming. Unlike the
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newer 28C EEPROMs, these chips do not automatically erase before writing to a location.
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Instead, the entire chip is erased by applying 14V to _VPP_ and _A9_ and then pulsing
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_CE_.
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Unlike the 257 chips, the W27C512 does not have a dedicated pin for the programming
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voltage and instead uses the OE pin to place the chip in programming mode. The verify
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operation requires that the OE pin be switched to _LOW_ and there is no hardware support
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for this, so the current code supports the 512 chip by doing a single write cycle with no
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verify.
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Because the chips use a constant high voltage for programming instead of a pulse, an
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external power supply and two diodes can be used to supply either 5V or 12V to the
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pins for programming and erasing.
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Note that the W27x257 chip are almost a drop-in replacement for the 28C256. The _WE_,
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_VPP_, and _A14_ pins are the only differences. For reading, the _VPP_ pin should be
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connected to 5V.
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#### 29C010
|
||||
|
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The 29C0x0 chips are 5V sectored flash chips. They automatically erase a sector at the
|
||||
start of a new write, so they can be used with the default 28C code.
|
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|
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Note that some versions of the 29C040 use a 256 byte sector size. This will not work
|
||||
with the TommyPROM code because the XModem transfer buffer is only 128 bytes. Code
|
||||
changes would be needed to buffer up two packets of data into a single write operation
|
||||
for chips with the 256 byte buffer.
|
||||
These chips cannot be erased and re-written, but they can be read by TommyPROM.
|
||||
Interesting trivia - some of the field-programmable OTPs are just EPROMs packaged without
|
||||
the erase window.
|
||||
|
||||
Loading…
Reference in New Issue
Block a user