1 files changed, 150 insertions, 0 deletions
diff --git a/protocol/ibm4704.c b/protocol/ibm4704.c
new file mode 100644
index 000000000..26441ed52
--- /dev/null
+++ b/protocol/ibm4704.c
@@ -0,0 +1,150 @@
+/*
+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)
+{
+    // POR
+    //_delay_ms(2500);
+    //while ( 0xA3 != ibm4704_recv() ) ;
+
+    inhibit();
+    DDRD |= 1<<3;
+    PORTD &= ~(1<<3);
+}
+
+uint8_t ibm4704_send(uint8_t data)
+{
+    bool parity = true; // odd parity
+    ibm4704_error = 0;
+
+    /* Request to send */
+    idle();
+    clock_lo();
+PIND |= 1<<3;
+
+    /* 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, 0x31);
+        //_delay_us(5);
+PIND |= 1<<3;
+        if (data&(1<<i)) {
+            parity = !parity;
+            data_hi();
+        } else {
+            data_lo();
+        }
+        WAIT(clock_lo, 100, 0x32);
+    }
+
+    /* Parity bit */
+    WAIT(clock_hi, 100, 4);
+PIND |= 1<<3;
+    if (parity) { data_hi(); } else { data_lo(); }
+    WAIT(clock_lo, 100, 5);
+
+    /* Stop bit */
+    WAIT(clock_hi, 100, 4);
+    data_hi();
+
+    /* End */
+    WAIT(data_lo, 100, 6);
+
+    inhibit();
+    _delay_us(200); // wait to recover clock to hi
+    return 0;
+ERROR:
+    inhibit();
+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:
+Clock   ~~~~___~~_~~_~~_~~_~~_~~_~~_~~_~~_~~~~~~~~ H:60us/L:30us
+
+Data    ____~~X==X==X==X==X==X==X==X==X==X________
+            |  0  1  2  3  4  5  6  7  P(odd)
+            |  LSB                MSB
+            Start bit(80us)
+*/
+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, 1); // wait for keyboard to send
+    WAIT(data_hi, 100, 2);  // can be delayed that long
+
+    WAIT(clock_hi, 100, 3); // 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, 7);
+    if (data_in() != parity) {
+        ibm4704_error = IBM4704_ERR_PARITY;
+        goto ERROR;
+    }
+    WAIT(clock_lo, 150, 8);
+
+    /* stop bit */
+    WAIT(clock_hi, 100, 9);
+    WAIT(data_lo, 1, 9);
+
+    inhibit();
+    _delay_us(200); // wait to recover clock to hi
+    return data;
+ERROR:
+    if (ibm4704_error > 2) {
+        xprintf("x%02X ", ibm4704_error);
+    }
+    inhibit();
+    _delay_us(200); // wait to recover clock to hi
+    return -1;
+}