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-rw-r--r--tmk_core/protocol/ibm4704.c169
1 files changed, 169 insertions, 0 deletions
diff --git a/tmk_core/protocol/ibm4704.c b/tmk_core/protocol/ibm4704.c
new file mode 100644
index 000000000..10e229fd1
--- /dev/null
+++ b/tmk_core/protocol/ibm4704.c
@@ -0,0 +1,169 @@
+/*
+Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
+*/
+#include <stdbool.h>
+#include <util/delay.h>
+#include "debug.h"
+#include "ibm4704.h"
+
+
+#define WAIT(stat, us, err) do { \
+ if (!wait_##stat(us)) { \
+ ibm4704_error = err; \
+ goto ERROR; \
+ } \
+} while (0)
+
+
+uint8_t ibm4704_error = 0;
+
+
+void ibm4704_init(void)
+{
+ inhibit();
+}
+
+/*
+Host to Keyboard
+----------------
+Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
+
+ ____ __ __ __ __ __ __ __ __ __ ________
+Clock \______/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
+ ^ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ___
+Data ____|__/ X____X____X____X____X____X____X____X____X____X \___
+ | Start 0 1 2 3 4 5 6 7 P Stop
+ Request by host
+
+Start bit: can be long as 300-350us.
+Request: Host pulls Clock line down to request to send a command.
+Timing: After Request keyboard pull up Data and down Clock line to low for start bit.
+ After request host release Clock line once Data line becomes hi.
+ Host writes a bit while Clock is hi and Keyboard reads while low.
+Stop bit: Host releases or pulls up Data line to hi after 9th clock and waits for keyboard pull down the line to lo.
+*/
+uint8_t ibm4704_send(uint8_t data)
+{
+ bool parity = true; // odd parity
+ ibm4704_error = 0;
+
+ /* Request to send */
+ idle();
+ clock_lo();
+
+ /* wait for Start bit(Clock:lo/Data:hi) */
+ WAIT(data_hi, 300, 0x30);
+
+ /* Data bit */
+ for (uint8_t i = 0; i < 8; i++) {
+ WAIT(clock_hi, 100, 0x40+i);
+ //_delay_us(5);
+ if (data&(1<<i)) {
+ parity = !parity;
+ data_hi();
+ } else {
+ data_lo();
+ }
+ WAIT(clock_lo, 100, 0x48+i);
+ }
+
+ /* Parity bit */
+ WAIT(clock_hi, 100, 0x34);
+ if (parity) { data_hi(); } else { data_lo(); }
+ WAIT(clock_lo, 100, 0x35);
+
+ /* Stop bit */
+ WAIT(clock_hi, 100, 0x34);
+ data_hi();
+
+ /* End */
+ WAIT(data_lo, 100, 0x36);
+
+ inhibit();
+ _delay_us(200); // wait to recover clock to hi
+ return 0;
+ERROR:
+ inhibit();
+ if (ibm4704_error >= 0x30) {
+ xprintf("x%02X ", ibm4704_error);
+ }
+ _delay_us(200); // wait to recover clock to hi
+ return -1;
+}
+
+/* receive data when host want else inhibit communication */
+uint8_t ibm4704_recv_response(void)
+{
+ // 250 * 100us(wait start bit in ibm4704_recv)
+ uint8_t data = 0;
+ uint8_t try = 250;
+ do {
+ data = ibm4704_recv();
+ } while (try-- && ibm4704_error);
+ return data;
+}
+
+/*
+Keyboard to Host
+----------------
+Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
+
+ ____ __ __ __ __ __ __ __ __ __ ________
+Clock \____/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/
+ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____
+Data ____/ X____X____X____X____X____X____X____X____X____X________
+ Start 0 1 2 3 4 5 6 7 P Stop
+
+Start bit: can be long as 300-350us.
+Inhibit: Pull Data line down to inhibit keyboard to send.
+Timing: Host reads bit while Clock is hi.
+Stop bit: Keyboard pulls down Data line to lo after 9th clock.
+*/
+uint8_t ibm4704_recv(void)
+{
+ uint8_t data = 0;
+ bool parity = true; // odd parity
+ ibm4704_error = IBM4704_ERR_NONE;
+
+ idle();
+ _delay_us(5); // wait for line settles
+
+ /* start bit */
+ WAIT(clock_lo, 100, 0x11); // wait for keyboard to send
+ WAIT(data_hi, 100, 0x12); // can be delayed that long
+
+ WAIT(clock_hi, 100, 0x13); // first rising edge which can take longer
+ /* data */
+ for (uint8_t i = 0; i < 8; i++) {
+ WAIT(clock_hi, 100, 0x20+i);
+ //_delay_us(5);
+ if (data_in()) {
+ parity = !parity;
+ data |= (1<<i);
+ }
+ WAIT(clock_lo, 150, 0x28+i);
+ }
+
+ /* parity */
+ WAIT(clock_hi, 100, 0x17);
+ if (data_in() != parity) {
+ ibm4704_error = IBM4704_ERR_PARITY;
+ goto ERROR;
+ }
+ WAIT(clock_lo, 150, 0x18);
+
+ /* stop bit */
+ WAIT(clock_hi, 100, 0x19);
+ WAIT(data_lo, 1, 0x19);
+
+ inhibit();
+ _delay_us(200); // wait to recover clock to hi
+ return data;
+ERROR:
+ if (ibm4704_error > 0x12) {
+ xprintf("x%02X ", ibm4704_error);
+ }
+ inhibit();
+ _delay_us(200); // wait to recover clock to hi
+ return -1;
+}