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[max/tmk_keyboard.git] / tmk_core / protocol / ibm4704.c

diff --git a/tmk_core/protocol/ibm4704.c b/tmk_core/protocol/ibm4704.c
index a2c6700477f97794676e0085c0865c15d4bb0c16..75e7db12b5e56aad7f8e84be9668735ee67203ae 100644 (file)
--- a/tmk_core/protocol/ibm4704.c
+++ b/tmk_core/protocol/ibm4704.c
@@ -21,9 +21,10 @@ uint8_t ibm4704_error = 0;
 
 void ibm4704_init(void)
 {
+    inhibit();  // keep keyboard from sending
     IBM4704_INT_INIT();
     IBM4704_INT_ON();
-    idle();
+    idle();     // allow keyboard sending
 }
 
 /*
@@ -38,7 +39,7 @@ 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.
+Start bit:  can be long as 300-350us during start up and upto 2500us while key scanning
 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.
@@ -57,7 +58,7 @@ uint8_t ibm4704_send(uint8_t data)
     clock_lo();
 
     /* wait for Start bit(Clock:lo/Data:hi) */
-    WAIT(data_hi, 300, 0x30);
+    WAIT(data_hi, 5000, 0x30);
 
     /* Data bit */
     for (uint8_t i = 0; i < 8; i++) {
@@ -88,7 +89,7 @@ uint8_t ibm4704_send(uint8_t data)
     return 0;
 ERROR:
     idle();
-    if (ibm4704_error > 0x30) {
+    if (ibm4704_error >= 0x30) {
         xprintf("S:%02X ", ibm4704_error);
     }
     IBM4704_INT_ON();
@@ -132,8 +133,8 @@ Stop bit:   Keyboard pulls down Data line to lo after 9th clock.
 ISR(IBM4704_INT_VECT)
 {
     static enum {
-        STOP, BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7, PARITY
-    } state = STOP;
+        BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7, PARITY, STOP
+    } state = BIT0;
     // LSB first
     static uint8_t data = 0;
     // Odd parity
@@ -141,11 +142,7 @@ ISR(IBM4704_INT_VECT)
 
     ibm4704_error = 0;
 
-    switch (state++) {
-        case STOP:
-            // Data:Low
-            WAIT(data_lo, 10, state);
-            break;
+    switch (state) {
         case BIT0:
         case BIT1:
         case BIT2:
@@ -166,6 +163,10 @@ ISR(IBM4704_INT_VECT)
             }
             if (!parity)
                 goto ERROR;
+            break;
+        case STOP:
+            // Data:Low
+            WAIT(data_lo, 100, state);
             rbuf_enqueue(data);
             ibm4704_error = IBM4704_ERR_NONE;
             goto DONE;
@@ -173,13 +174,14 @@ ISR(IBM4704_INT_VECT)
         default:
             goto ERROR;
     }
+    state++;
     goto RETURN;
 ERROR:
     ibm4704_error = state;
     while (ibm4704_send(0xFE)) _delay_ms(1); // resend
     xprintf("R:%02X%02X\n", state, data);
 DONE:
-    state = STOP;
+    state = BIT0;
     data = 0;
     parity = false;
 RETURN: