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Update README for 2560-based ASCII interface

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Dave 2020-05-12 17:43:44 -05:00
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hardware/interface-ascii-atmega2560/README.md
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@ -17,9 +17,9 @@ output, supporting keyboards of up to 16 rows X 8 columns. This design uses the
## Differences from ATMega328P version ## Differences from ATMega328P version
- Backward compatible with the ATMega328P version, with following enhancements: - Backward compatible with the ATMega328P version, with following enhancements:
1. The Output2 can be a regualar TTL, open-collector, or open-emitter. In the 1. All the TTL outputs can be regualar push-pull TTL, open-collector, or open-emitter. In the
328P version, changing between regular TTL output and open-collector on 328P version, changing between regular TTL output and open-collector on
Output2 required changing an IC. Output 2 required changing an IC.
1. The serial port no longer shares lines with the parallel output port, so both 1. The serial port no longer shares lines with the parallel output port, so both
serial I/O and parallel output can be used at the same time without risk of serial I/O and parallel output can be used at the same time without risk of
conflict. However, serial I/O is not yet supported in the firmware. conflict. However, serial I/O is not yet supported in the firmware.
@ -36,12 +36,13 @@ output, supporting keyboards of up to 16 rows X 8 columns. This design uses the
be RESET, BREAK, CLEAR, etc. These may be configured as open-collector (Hi-Z be RESET, BREAK, CLEAR, etc. These may be configured as open-collector (Hi-Z
for HI, GND for LO), or open-emitter (5V for high, Hi-Z for LO). for HI, GND for LO), or open-emitter (5V for high, Hi-Z for LO).
- Three GPIO lines are used to control keyboard LED, or other keyboard functions. - Three GPIO lines are used to control keyboard LED, or other keyboard functions.
- The DIP switch is wired into row 8 (of 0-15), to reduce RAM usage and speed up
key scanning.
- A serial (UART) port is provided. This could be used to provide serial output - A serial (UART) port is provided. This could be used to provide serial output
instead or parallel output, to support a bootloader, or even to accept a serial instead or parallel output, to support a bootloader, or even to accept a serial
input stream from another source to send to the host as parallel ASCII data. input stream from another source to send to the host as parallel ASCII data.
- JTAG port is provided for programming and debugging
- Two custom connectors (16-pin DIP and 1x25 0.1" header) are provided to allow
custom ASCII interfaces, or custom keyboard matrix interface.
## Assembly Notes ## Assembly Notes
1. Solder the surface-mount microcontroller first. Be sure to match pin 1 to the 1. Solder the surface-mount microcontroller first. Be sure to match pin 1 to the