3 files changed, 23 insertions, 26 deletions

diff --git a/converter/ibm4704_usb/config.h b/converter/ibm4704_usb/config.h
index 4f267b3b7..d9d8d39bc 100644
--- a/converter/ibm4704_usb/config.h
+++ b/converter/ibm4704_usb/config.h
@@ -51,8 +51,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define IBM4704_DATA_DDR    DDRD
 #define IBM4704_DATA_BIT    0
 
-/* Pin interrupt on  rising edge */
-#define IBM4704_INT_INIT()  do { EICRA |= ((1<<ISC11)|(0<<ISC10)); } while (0)
+/* Pin interrupt on rising edge of clock */
+#define IBM4704_INT_INIT()  do { EICRA |= ((1<<ISC11)|(1<<ISC10)); } while (0)
 #define IBM4704_INT_ON()    do { EIMSK |=  (1<<INT1); } while (0)
 #define IBM4704_INT_OFF()   do { EIMSK &= ~(1<<INT1); } while (0)
 #define IBM4704_INT_VECT    INT1_vect
diff --git a/converter/ibm4704_usb/ibm4704.txt b/converter/ibm4704_usb/ibm4704.txt
index 9c4895d92..50d8c98b0 100644
--- a/converter/ibm4704_usb/ibm4704.txt
+++ b/converter/ibm4704_usb/ibm4704.txt
@@ -57,15 +57,15 @@ Keyboard to Host
 ----------------
 Data bits are LSB first and Pairty is odd. Clock has around 60us high and 30us low part.
 
-            ____      __   __   __   __   __   __   __   __   __   ________
-    Clock       \____/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/
+            ____       __   __   __   __   __   __   __   __   __   _______
+    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.
+Timing:     Host reads bit while Clock is hi.(rising edge)
 Stop bit:   Keyboard pulls down Data line to lo after 9th clock.
 
 
diff --git a/tmk_core/protocol/ibm4704.c b/tmk_core/protocol/ibm4704.c
index a10a5e74d..a2c670047 100644
--- a/tmk_core/protocol/ibm4704.c
+++ b/tmk_core/protocol/ibm4704.c
@@ -104,50 +104,47 @@ uint8_t ibm4704_recv_response(void)
     return rbuf_dequeue();
 }
 
+uint8_t ibm4704_recv(void)
+{
+    if (rbuf_has_data()) {
+        return rbuf_dequeue();
+    } else {
+        return -1;
+    }
+}
+
 /*
 Keyboard to Host
 ----------------
 Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
 
-        ____      __   __   __   __   __   __   __   __   __   ________
-Clock       \____/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/  \_/
+        ____       __   __   __   __   __   __   __   __   __   _______
+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.
+Timing:     Host reads bit while Clock is hi.(rising edge)
 Stop bit:   Keyboard pulls down Data line to lo after 9th clock.
 */
-uint8_t ibm4704_recv(void)
-{
-    if (rbuf_has_data()) {
-        return rbuf_dequeue();
-    } else {
-        return -1;
-    }
-}
-
 ISR(IBM4704_INT_VECT)
 {
     static enum {
-        INIT, START, BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7, PARITY,
-    } state = INIT;
+        STOP, BIT0, BIT1, BIT2, BIT3, BIT4, BIT5, BIT6, BIT7, PARITY
+    } state = STOP;
     // LSB first
     static uint8_t data = 0;
     // Odd parity
     static uint8_t parity = false;
 
     ibm4704_error = 0;
-    // return unless falling edge
-    if (clock_in()) { goto RETURN; }    // why this occurs?
 
-    state++;
-    switch (state) {
-        case START:
+    switch (state++) {
+        case STOP:
             // Data:Low
-            WAIT(data_hi, 10, state);
+            WAIT(data_lo, 10, state);
             break;
         case BIT0:
         case BIT1:
@@ -182,7 +179,7 @@ ERROR:
     while (ibm4704_send(0xFE)) _delay_ms(1); // resend
     xprintf("R:%02X%02X\n", state, data);
 DONE:
-    state = INIT;
+    state = STOP;
     data = 0;
     parity = false;
 RETURN: