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unified_retro_keyboard
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break out separate section for 2560 encoder.

Dave 2021-08-12 21:22:14 -05:00
parent c7bb9cfb32
commit 4d19eb8bff
2 changed files with 38 additions and 1 deletions
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16
Home.md

@ -8,6 +8,7 @@ This wiki will collect technical notes, assembly and configuration guides, tips
[Apple II notes](apple-ii-notes)
[Encoder nodes (2560-based)](encoder-2560-notes)
<details>
<summary>Programming the Atmega chips</summary>
Make sure that the DIV8 flag is OFF (or the chip will run at 1 MHz and you will find the encoder to be very sluggish), and the ISP programming flag is enabled (if you want to be able to program via the ISP header)
@ -30,5 +31,18 @@ All other fuses disabled.
</details>
<details><summary>For ATMega2560</summary>
TO DO
Extended: 0xFF
High: 0x99
Low: 0xE7
This corresponds to the following fuse settings
- Brownout Detection Disabled (Extended byte)
- JTAGEN (in system programming over JTAG) Enabled (High byte)
- SPIEN (in system programming over SPI) Enabled (High byte)
- Boot flash size 4096 ((high byte)
- Full Swing Oscillator, xtal, fast rise, 4.1 ms startup (low byte)
All other fuses disabled.
</details>

23
encoder-2560-notes/encoder-2560-notes.md Normal file

@ -0,0 +1,23 @@
Fuse settings for the ATMega2560:
Extended: 0xFF
High: 0x99
Low: 0xE7
This corresponds to the following fuse settings
- Brownout Detection Disabled (Extended byte)
- JTAGEN (in system programming over JTAG) Enabled (High byte)
- SPIEN (in system programming over SPI) Enabled (High byte)
- Boot flash size 4096 ((high byte)
- Full Swing Oscillator, xtal, fast rise, 4.1 ms startup (low byte)
All other fuses disabled.
Errata:
<details><summary>rev 4.2:</summary>
The footprints for D1-D16 are supposed to have a shorting jumper trace built in. For keyboards with a diode installed per-key, these diodes are not installed. Since the jumpers are not pre-configured, wire jumpers must be installed in the D1-D16 positions for the keyboard to scan correctly.
If you are using a keyboard without any built-in diodes (such as a prefabricated key matrix), then install the diodes D1-D16 (1n914, in4148, or similar) to protect the row-scanning TTL outputs from conflicting logic levels in the event of simultaneous keypresses.
</details>