Revision: 4362 Author: hans URL: http://bknr.net/trac/changeset/4362

comments U trunk/projects/symbolics-keyboard/teensy-firmware/symbolics.c

Modified: trunk/projects/symbolics-keyboard/teensy-firmware/symbolics.c =================================================================== --- trunk/projects/symbolics-keyboard/teensy-firmware/symbolics.c 2009-04-07 06:04:35 UTC (rev 4361) +++ trunk/projects/symbolics-keyboard/teensy-firmware/symbolics.c 2009-04-07 07:21:12 UTC (rev 4362) @@ -1,5 +1,29 @@ -/* Symbolics keyboard adapter, based on Teensy keyboard example */ +// -*- C++ -*- (this is really C)

+// Symbolics keyboard adapter, based on Teensy keyboard example. + +// The Symbolics keyboard acts as a shift register with 128 bits. The +// hardware interface consists of a clear line which is used to signal +// the beginning of a read cycle, a clock line, and a data line. All +// signals are active low. The keyboard changes the data line on the +// rising edge of the clock. It should be read near the falling edge +// of the clock by the host. + +// The keyboard needs to be interfaced to the Teensy board as +// follows. The wire colors specified are those used in the original +// modular cable supplied with the keyboard: +// +// blue 5V +// green GND +// red D4 DIN +// black D5 CLK +// white D6 CK] + +// The keyboard implements two locking functions, caps lock and mode +// lock. Both of these are implemented as switches, not as buttons, +// so precautions must be made to synchronize their state to the +// host's caps lock state. + /* Keyboard example for Teensy USB Development Board * http://www.pjrc.com/teensy/usb_keyboard.html * Copyright (c) 2008 PJRC.COM, LLC @@ -103,6 +127,10 @@ void report_version(void) { + // Report Subversion revision number. We only convert the revision + // number and do not bother to convert other characters to key + // presses. + int i = 0; for (;;) { uint8_t c = pgm_read_byte(&revision[i++]); @@ -143,13 +171,19 @@ void send_keys(uint8_t* state) { + // A change of state has been detected by the main loop, report all + // currently pressed keys to the host. + uint8_t local = 0; uint8_t caps_lock_pressed = 0; const uint8_t* keymap = keymap_normal;

retry: // If we detect that we are in f-mode, we need to translate the - // pressed keys with the f-mode translation table. + // pressed keys with the f-mode translation table. Detection of + // f-mode happens while decoding the shift register. When the + // f-mode key is detected as being pressed, the translation table is + // switched and the decoding process is restarted. { uint8_t key_index = 0; uint8_t map_index = 0;