98 lines
3.6 KiB
Markdown
98 lines
3.6 KiB
Markdown
# Stowaway Serial keyboard to USB protocol converter
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A converter for Palm Pilot era Stowaway serial keyboards.
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Makes extensive use of the code from [cy384](https://github.com/cy384/ppk_usb). Ported to QMK by [milestogo](https://github.com/milestogo).
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Hardware Supported: See hardware section below
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Hardware Availability: self-built
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Make example for this keyboard (after setting up your build environment):
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make converter/palm_usb/stowaway:default
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See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
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## Hardware
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Target MCU is ATMega32u4 but other USB capable AVRs should also work.
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cy843 has a very specific way of wiring in order to fit all pins in sequence. It breaks
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qmk because the Arduino softserial library uses different pins from QMK.
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I've wired the pro micro hardware as follows.
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| Label | TX0 | RX1 | GND | GND | 2 | 3 | 4 | 5 | 6 | 7 |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| Palm | | | * | GND | VCC | RX | NC | RTS | NC | DCD |
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| MCU | | | | | D1 | D0 | | C6 | | E6 |
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\* The RX line from the keyboard should be conected to a ~10K ohm pull down resistor to ground.
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RX --|--3
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10K
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GND
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Power management is not implemented yet, this just reboots the keyboard frequently.
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### Keyboards:
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Think Outside Stowaway Keyboards
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There are at least 5 different versions of these keyboards out there.
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Group 1: Palm 3, Palm 5 & HP Journada 540, and Compaq iPaq keyboards. These share
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the same RTS protocol, but with different pinouts for each device.
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Group 2: Handspring keyboards. These don't do handshaking protocol, and use TTL signal.
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Set HANDSPRING to 1 in config.h
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Group 3: IRDA models. Untested but theoretically serial.
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### Connectors
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See https://github.com/cy384/ppk_usb for wiring & sample 3d printable sockets.
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Only Palm3 wiring has been tested.
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RXD pin is output from keyboard to MCU's RX.
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Viewed from left to right with the keyboard in typing position.
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Palm3: [NC, VCC, RXD, RTS, NC, NC, DCD, NC, NC, GND]
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Palm5: [NC, VCC, RXD, RTS, NC, NC, DCD, NC, NC, GND] (same order, different connector)
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Handspring: [VCC/TXD, NC, NC, NC, GND, NC, NC, RXD]
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Journada: [NC, NC, NC, GND, NC, RTS, NC, DTR/VCC, RXD, DCD, NC] [GND-IN, VCC-IN]
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Ipaq: [NC, NC, DTR/VCC, NC, NC, RTS, NC, RXD, DCD, GND, NC, NC]
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### Protocol
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Signal: Asynchronous, Negative logic, 9600baud, No Flow control
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Frame format: 1-Start bit, 8-Data bits, No-Parity, 1-Stop bit
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AVR USART engine expects positive logic while stowaway keyboard signal is negative.
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To use AVR UART engine you need external inverter in front of RX and TX pin.
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Otherwise you can software serial routine to communicate the keyboard.
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This converter uses software method, you doesn't need any inverter part.
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Commands From System To Keyboard
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none
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Commands From Keyboard To System
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0xFA Reset/Ready Response(followed by 0xFD)
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References
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* http://www.splorp.com/pdf/stowawayhwref.pdf
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### Todo
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- Test on anything but a palm 3 model keyboard.
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- Change all of the soft serial to match the new Helix based code so that it is easier
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to switch pins.
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- The driver should check for a keyboard that pressed the delete key then disconnected.
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Check every MAXDROP scans that the keyboard is there, and if not, clear the matrix.
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Not implemented yet, since matrix scan is so much faster than serial.
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