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79 lines
2.1 KiB
Markdown
79 lines
2.1 KiB
Markdown
---
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title: Troubleshooting
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has_children: false
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nav_order: 3
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---
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## Hardware Verifier Tool
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A [Hardware verification Arduino sketch](https://github.com/TomNisbet/TommyPROM/tree/master/HardwareVerify)
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is provided to assist with troubleshooting. Loading this sketch onto the TommyPROM
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hardware allows access to individual control lines from the Arduino to verify that the
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hardware was assembled correctly.
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The verifier sketch can be used without a chip installed to scope out address and data
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lines. It also offers low-level control when the chip is installed.
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THIS TOOL USES DIRECT PORT ACCESS ON THE ARDUINO. CHECK TO MAKE SURE IT IS COMPATIBLE
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WITH YOUR BOARD BEFORE USING. It will work correctly on the Unu, Nano, and Boarduino. It
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WILL NOT WORK on the Micro.
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Note that the commands write to the individual 28C control lines with some exceptions to
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protect the chip and the host Arduino:
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* When the O command is used to enable chip output, the Arduino data bus is set to INPUT
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* When the D command is used to write data from the Arduino, the chip output is disabled
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* The R command sets the output enable (OE) on the chip, but not the chip enable (CE)
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* The L and U commands reset CE, OE, and WE back to disabled on completion and change the
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data and address
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The session below shows how a write fails to a locked chip and then succeeds once the chip
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is unlocked.
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```
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Hardware Verifier - 28C series EEPROM
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Valid commands are:
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Axxxx - Set address bus to xxxx
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Dxx - Set Data bus to xx
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Cs - Set Chip enable to state (e=enable, d=disable)
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Os - Set Output enable to state (e=enable, d=disable)
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Ws - Set Write enable to state (e=enable, d=disable)
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R - Read and print the value on the data bus
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L - Send Lock sequence to enable device Software Data Protection
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U - Send Unlock sequence to disable device Software Data Protection
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#l
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Writing the lock code to enable Software Write Protect mode.
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#a0000
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#ce
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#r
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22
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#d55
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#we
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#wd
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#r
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22
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#u
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Writing the unlock code to disable Software Write Protect mode.
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#d33
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#we
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#wd
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#r
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33
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#cd
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```
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