From 4150bec5c95ce96bfb24de2496fd0f2c150960ca Mon Sep 17 00:00:00 2001
From: tmk <nobody@nowhere>
Date: Sun, 9 Feb 2014 02:42:17 +0900
Subject: [PATCH 1/4] Add Initial files of 4704_usb

---
 protocol/ibm4704.c | 150 +++++++++++++++++++++++++++++++++++++++++++++
 protocol/ibm4704.h | 111 +++++++++++++++++++++++++++++++++
 2 files changed, 261 insertions(+)
 create mode 100644 protocol/ibm4704.c
 create mode 100644 protocol/ibm4704.h

diff --git a/protocol/ibm4704.c b/protocol/ibm4704.c
new file mode 100644
index 00000000..26441ed5
--- /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;
+}
diff --git a/protocol/ibm4704.h b/protocol/ibm4704.h
new file mode 100644
index 00000000..ff8a5b77
--- /dev/null
+++ b/protocol/ibm4704.h
@@ -0,0 +1,111 @@
+/*
+Copyright 2014 Jun WAKO <wakojun@gmail.com>
+*/
+#ifndef IBM4704_H
+#define IBM4704_H
+
+#define IBM4704_ERR_NONE        0
+#define IBM4704_ERR_STARTBIT    1
+#define IBM4704_ERR_PARITY      0x70
+
+
+void ibm4704_init(void);
+uint8_t ibm4704_send(uint8_t data);
+uint8_t ibm4704_recv_response(void);
+uint8_t ibm4704_recv(void);
+
+
+/* Check pin configuration */
+#if !(defined(IBM4704_CLOCK_PORT) && \
+      defined(IBM4704_CLOCK_PIN) && \
+      defined(IBM4704_CLOCK_DDR) && \
+      defined(IBM4704_CLOCK_BIT))
+#   error "ibm4704 clock pin configuration is required in config.h"
+#endif
+
+#if !(defined(IBM4704_DATA_PORT) && \
+      defined(IBM4704_DATA_PIN) && \
+      defined(IBM4704_DATA_DDR) && \
+      defined(IBM4704_DATA_BIT))
+#   error "ibm4704 data pin configuration is required in config.h"
+#endif
+
+
+/*--------------------------------------------------------------------
+ * static functions
+ *------------------------------------------------------------------*/
+static inline void clock_lo(void)
+{
+    IBM4704_CLOCK_PORT &= ~(1<<IBM4704_CLOCK_BIT);
+    IBM4704_CLOCK_DDR  |=  (1<<IBM4704_CLOCK_BIT);
+}
+static inline void clock_hi(void)
+{
+    /* input with pull up */
+    IBM4704_CLOCK_DDR  &= ~(1<<IBM4704_CLOCK_BIT);
+    IBM4704_CLOCK_PORT |=  (1<<IBM4704_CLOCK_BIT);
+}
+static inline bool clock_in(void)
+{
+    IBM4704_CLOCK_DDR  &= ~(1<<IBM4704_CLOCK_BIT);
+    IBM4704_CLOCK_PORT |=  (1<<IBM4704_CLOCK_BIT);
+    _delay_us(1);
+    return IBM4704_CLOCK_PIN&(1<<IBM4704_CLOCK_BIT);
+}
+static inline void data_lo(void)
+{
+    IBM4704_DATA_PORT &= ~(1<<IBM4704_DATA_BIT);
+    IBM4704_DATA_DDR  |=  (1<<IBM4704_DATA_BIT);
+}
+static inline void data_hi(void)
+{
+    /* input with pull up */
+    IBM4704_DATA_DDR  &= ~(1<<IBM4704_DATA_BIT);
+    IBM4704_DATA_PORT |=  (1<<IBM4704_DATA_BIT);
+}
+static inline bool data_in(void)
+{
+    IBM4704_DATA_DDR  &= ~(1<<IBM4704_DATA_BIT);
+    IBM4704_DATA_PORT |=  (1<<IBM4704_DATA_BIT);
+    _delay_us(1);
+    return IBM4704_DATA_PIN&(1<<IBM4704_DATA_BIT);
+}
+
+static inline uint16_t wait_clock_lo(uint16_t us)
+{
+    while (clock_in()  && us) { asm(""); _delay_us(1); us--; }
+    return us;
+}
+static inline uint16_t wait_clock_hi(uint16_t us)
+{
+    while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
+    return us;
+}
+static inline uint16_t wait_data_lo(uint16_t us)
+{
+    while (data_in() && us)  { asm(""); _delay_us(1); us--; }
+    return us;
+}
+static inline uint16_t wait_data_hi(uint16_t us)
+{
+    while (!data_in() && us)  { asm(""); _delay_us(1); us--; }
+    return us;
+}
+
+/* idle state that device can send */
+static inline void idle(void)
+{
+    clock_hi();
+    data_hi();
+}
+
+/* inhibit device to send 
+ * keyboard checks Data line on start bit(Data:hi) and it stops sending if Data line is low.
+ */
+static inline void inhibit(void)
+{
+    clock_hi();
+    data_lo();
+}
+
+#endif

From 22e0d9785e064c3e831512133ac97485b8bdd53b Mon Sep 17 00:00:00 2001
From: tmk <nobody@nowhere>
Date: Mon, 10 Feb 2014 06:43:43 +0900
Subject: [PATCH 2/4] Change error no and clean debug code

---
 protocol/ibm4704.c | 41 +++++++++++++++++------------------------
 protocol/ibm4704.h |  1 -
 2 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/protocol/ibm4704.c b/protocol/ibm4704.c
index 26441ed5..d3fbcc54 100644
--- a/protocol/ibm4704.c
+++ b/protocol/ibm4704.c
@@ -20,13 +20,7 @@ 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)
@@ -37,44 +31,43 @@ uint8_t ibm4704_send(uint8_t data)
     /* 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);
+        WAIT(clock_hi, 100, 0x40+i);
         //_delay_us(5);
-PIND |= 1<<3;
         if (data&(1<<i)) {
             parity = !parity;
             data_hi();
         } else {
             data_lo();
         }
-        WAIT(clock_lo, 100, 0x32);
+        WAIT(clock_lo, 100, 0x48+i);
     }
 
     /* Parity bit */
-    WAIT(clock_hi, 100, 4);
-PIND |= 1<<3;
+    WAIT(clock_hi, 100, 0x34);
     if (parity) { data_hi(); } else { data_lo(); }
-    WAIT(clock_lo, 100, 5);
+    WAIT(clock_lo, 100, 0x35);
 
     /* Stop bit */
-    WAIT(clock_hi, 100, 4);
+    WAIT(clock_hi, 100, 0x34);
     data_hi();
 
     /* End */
-    WAIT(data_lo, 100, 6);
+    WAIT(data_lo, 100, 0x36);
 
     inhibit();
     _delay_us(200); // wait to recover clock to hi
     return 0;
 ERROR:
     inhibit();
-xprintf("x%02X ", ibm4704_error);
+    if (ibm4704_error >= 0x30) {
+        xprintf("x%02X ", ibm4704_error);
+    }
     _delay_us(200); // wait to recover clock to hi
     return -1;
 }
@@ -110,10 +103,10 @@ uint8_t ibm4704_recv(void)
     _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_lo, 100, 0x11); // wait for keyboard to send
+    WAIT(data_hi, 100, 0x12);  // can be delayed that long
 
-    WAIT(clock_hi, 100, 3); // first rising edge which can take longer
+    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);
@@ -126,22 +119,22 @@ uint8_t ibm4704_recv(void)
     }
 
     /* parity */
-    WAIT(clock_hi, 100, 7);
+    WAIT(clock_hi, 100, 0x17);
     if (data_in() != parity) {
         ibm4704_error = IBM4704_ERR_PARITY;
         goto ERROR;
     }
-    WAIT(clock_lo, 150, 8);
+    WAIT(clock_lo, 150, 0x18);
 
     /* stop bit */
-    WAIT(clock_hi, 100, 9);
-    WAIT(data_lo, 1, 9);
+    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 > 2) {
+    if (ibm4704_error > 0x12) {
         xprintf("x%02X ", ibm4704_error);
     }
     inhibit();
diff --git a/protocol/ibm4704.h b/protocol/ibm4704.h
index ff8a5b77..618cce6b 100644
--- a/protocol/ibm4704.h
+++ b/protocol/ibm4704.h
@@ -5,7 +5,6 @@ Copyright 2014 Jun WAKO <wakojun@gmail.com>
 #define IBM4704_H
 
 #define IBM4704_ERR_NONE        0
-#define IBM4704_ERR_STARTBIT    1
 #define IBM4704_ERR_PARITY      0x70
 
 

From 464caa1c31b0e37f56a4b087e6ddbd5ac43eb28d Mon Sep 17 00:00:00 2001
From: tmk <nobody@nowhere>
Date: Mon, 10 Feb 2014 11:05:18 +0900
Subject: [PATCH 3/4] Add doc 4704.txt and protocol comment

---
 protocol/ibm4704.c | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/protocol/ibm4704.c b/protocol/ibm4704.c
index d3fbcc54..10e229fd 100644
--- a/protocol/ibm4704.c
+++ b/protocol/ibm4704.c
@@ -23,6 +23,25 @@ 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
@@ -85,13 +104,20 @@ uint8_t ibm4704_recv_response(void)
 }
 
 /*
-Keyboard to Host:
-Clock   ~~~~___~~_~~_~~_~~_~~_~~_~~_~~_~~_~~~~~~~~ H:60us/L:30us
+Keyboard to Host
+----------------
+Data bits are LSB first and Parity is odd. Clock has around 60us high and 30us low part.
 
-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)
+        ____      __   __   __   __   __   __   __   __   __   ________
+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)
 {

From 622b6d891b6005c30441b9e1d20802c788924e9d Mon Sep 17 00:00:00 2001
From: tmk <nobody@nowhere>
Date: Thu, 13 Feb 2014 09:45:02 +0900
Subject: [PATCH 4/4] Add converter/ibm4704_usb

---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index b76b7fb9..a561b38e 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,7 @@ You can find some keyboard specific projects under `converter` and `keyboard` di
 * [pc98_usb](converter/pc98_usb/)           - [PC98] to USB
 * [usb_usb](converter/usb_usb/)             - USB to USB(experimental)
 * [ascii_usb](converter/ascii_usb/)         - ASCII(Serial console terminal) to USB
+* [ibm4704_usb](converter/ibm4704_usb)      - [IBM 4704 keyboard Converter][GH_ibm4704]
 
 ### keyboard
 * [hhkb](keyboard/hhkb/)                    - [Happy Hacking Keyboard pro][GH_hhkb] **my main board**
@@ -62,6 +63,7 @@ You can find some keyboard specific projects under `converter` and `keyboard` di
 [GH_terminal]:  http://geekhack.org/showwiki.php?title=Island:27272
 [GH_x68k]:      http://geekhack.org/showwiki.php?title=Island:29060
 [GH_hbkb]:      http://geekhack.org/showwiki.php?title=Island:29483
+[GH_ibm4704]:   http://geekhack.org/index.php?topic=54706.0
 [HID_liber]:    http://deskthority.net/wiki/HID_Liberation_Device_-_DIY_Instructions
 [Phantom]:      http://geekhack.org/index.php?topic=26742
 [GH60]:         http://geekhack.org/index.php?topic=34959