Merge remote-tracking branch 'origin/master' into develop

8 files changed, 89 insertions, 526 deletions

diff --git a/keyboards/3w6/rev1/matrix.c b/keyboards/3w6/rev1/matrix.c
index 7262fd22e..af3d21067 100644
--- a/keyboards/3w6/rev1/matrix.c
+++ b/keyboards/3w6/rev1/matrix.c
@@ -35,8 +35,6 @@ extern i2c_status_t tca9555_status;
 // | 0  | 1  | 0  | 0  | A2 | A1 | A0 |
 // | 0  | 1  | 0  | 0  | 0  | 0  | 0  |
 #define I2C_ADDR 0b0100000
-#define I2C_ADDR_WRITE ((I2C_ADDR << 1) | I2C_WRITE)
-#define I2C_ADDR_READ ((I2C_ADDR << 1) | I2C_READ)
 
 // Register addresses
 #define IODIRA 0x06  // i/o direction register
@@ -64,19 +62,14 @@ uint8_t init_tca9555(void) {
     // - unused  : input  : 1
     // - input   : input  : 1
     // - driving : output : 0
-    tca9555_status = i2c_start(I2C_ADDR_WRITE, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-    tca9555_status = i2c_write(IODIRA, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-    // This means: write on pin 5 of port 0, read on rest
-    tca9555_status = i2c_write(0b11011111, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-    // This means: we will write on pins 0 to 2 on port 1. read rest
-    tca9555_status = i2c_write(0b11111000, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-
-out:
-    i2c_stop();
+    uint8_t conf[2] = {
+        // This means: write on pin 5 of port 0, read on rest
+        0b11011111,
+        // This means: we will write on pins 0 to 2 on port 1. read rest
+        0b11111000,
+    };
+    tca9555_status = i2c_writeReg(I2C_ADDR, IODIRA, conf, 2, I2C_TIMEOUT);
+
     return tca9555_status;
 }
 
@@ -192,36 +185,29 @@ static matrix_row_t read_cols(uint8_t row) {
         if (tca9555_status) {  // if there was an error
             return 0;
         } else {
-            uint8_t data    = 0;
-            uint8_t port0   = 0;
-            uint8_t port1   = 0;
-            tca9555_status = i2c_start(I2C_ADDR_WRITE, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(IREGP0, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_start(I2C_ADDR_READ, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_read_ack(I2C_TIMEOUT);
-            if (tca9555_status < 0) goto out;
-            port0 = (uint8_t)tca9555_status;
-            tca9555_status = i2c_read_nack(I2C_TIMEOUT);
-            if (tca9555_status < 0) goto out;
-            port1 = (uint8_t)tca9555_status;
-
-            // The initial state was all ones and any depressed key at a given column for the currently selected row will have its bit flipped to zero.
-            // The return value is a row as represented in the generic matrix code were the rightmost bits represent the lower columns and zeroes represent non-depressed keys while ones represent depressed keys.
-            // Since the pins are not ordered sequentially, we have to build the correct dataset from the two ports. Refer to the schematic to see where every pin is connected.
-            data |= ( port0 & 0x01 ); 
-            data |= ( port0 & 0x02 ); 
-            data |= ( port1 & 0x10 ) >> 2; 
-            data |= ( port1 & 0x08 ); 
-            data |= ( port0 & 0x40 ) >> 2; 
-            data = ~(data);
-
-            tca9555_status = I2C_STATUS_SUCCESS;
-        out:
-            i2c_stop();
-            return data;
+            uint8_t data     = 0;
+            uint8_t ports[2] = {0};
+            tca9555_status = i2c_readReg(I2C_ADDR, IREGP0, ports, 2, I2C_TIMEOUT);
+            if (tca9555_status) {  // if there was an error
+                // do nothing
+                return 0;
+            } else {
+                uint8_t port0 = ports[0];
+                uint8_t port1 = ports[1];
+
+                // The initial state was all ones and any depressed key at a given column for the currently selected row will have its bit flipped to zero.
+                // The return value is a row as represented in the generic matrix code were the rightmost bits represent the lower columns and zeroes represent non-depressed keys while ones represent depressed keys.
+                // Since the pins are not ordered sequentially, we have to build the correct dataset from the two ports. Refer to the schematic to see where every pin is connected.
+                data |= ( port0 & 0x01 ); 
+                data |= ( port0 & 0x02 ); 
+                data |= ( port1 & 0x10 ) >> 2; 
+                data |= ( port1 & 0x08 ); 
+                data |= ( port0 & 0x40 ) >> 2; 
+                data = ~(data);
+
+                tca9555_status = I2C_STATUS_SUCCESS;
+                return data;
+            }
         }
     }
 }
@@ -263,18 +249,10 @@ static void select_row(uint8_t row) {
                 default:                    break;
             }
 
-            tca9555_status = i2c_start(I2C_ADDR_WRITE, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(OREGP0, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(port0, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(port1, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
+            uint8_t ports[2] = {port0, port1};
+            tca9555_status = i2c_writeReg(I2C_ADDR, OREGP0, ports, 2, I2C_TIMEOUT);
             // Select the desired row by writing a byte for the entire GPIOB bus where only the bit representing the row we want to select is a zero (write instruction) and every other bit is a one.
             // Note that the row - MATRIX_ROWS_PER_SIDE reflects the fact that being on the right hand, the columns are numbered from MATRIX_ROWS_PER_SIDE to MATRIX_ROWS, but the pins we want to write to are indexed from zero up on the GPIOB bus.
-        out:
-            i2c_stop();
         }
     }
 }
diff --git a/keyboards/3w6/rev2/matrix.c b/keyboards/3w6/rev2/matrix.c
index 5bc967bed..4df161b89 100644
--- a/keyboards/3w6/rev2/matrix.c
+++ b/keyboards/3w6/rev2/matrix.c
@@ -35,8 +35,6 @@ extern i2c_status_t tca9555_status;
 // | 0  | 1  | 0  | 0  | A2 | A1 | A0 |
 // | 0  | 1  | 0  | 0  | 0  | 0  | 0  |
 #define I2C_ADDR 0b0100000
-#define I2C_ADDR_WRITE ((I2C_ADDR << 1) | I2C_WRITE)
-#define I2C_ADDR_READ ((I2C_ADDR << 1) | I2C_READ)
 
 // Register addresses
 #define IODIRA 0x06  // i/o direction register
@@ -64,19 +62,14 @@ uint8_t init_tca9555(void) {
     // - unused  : input  : 1
     // - input   : input  : 1
     // - driving : output : 0
-    tca9555_status = i2c_start(I2C_ADDR_WRITE, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-    tca9555_status = i2c_write(IODIRA, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-    // This means: read all pins of port 0
-    tca9555_status = i2c_write(0b11111111, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-    // This means: we will write on pins 0 to 3 on port 1. read rest
-    tca9555_status = i2c_write(0b11110000, I2C_TIMEOUT);
-    if (tca9555_status) goto out;
-
-out:
-    i2c_stop();
+    uint8_t conf[2] = {
+        // This means: read all pins of port 0
+        0b11111111,
+        // This means: we will write on pins 0 to 3 on port 1. read rest
+        0b11110000,
+    };
+    tca9555_status = i2c_writeReg(I2C_ADDR, IODIRA, conf, 2, I2C_TIMEOUT);
+
     return tca9555_status;
 }
 
@@ -194,32 +187,27 @@ static matrix_row_t read_cols(uint8_t row) {
         } else {
             uint8_t data    = 0;
             uint8_t port0   = 0;
-            tca9555_status = i2c_start(I2C_ADDR_WRITE, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(IREGP0, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_start(I2C_ADDR_READ, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_read_nack(I2C_TIMEOUT);
-            if (tca9555_status < 0) goto out;
-            
-            port0 = ~(uint8_t)tca9555_status;
-
-            // We read all the pins on GPIOA.
-            // The initial state was all ones and any depressed key at a given column for the currently selected row will have its bit flipped to zero.
-            // The return value is a row as represented in the generic matrix code were the rightmost bits represent the lower columns and zeroes represent non-depressed keys while ones represent depressed keys.
-            // the pins connected to eact columns are sequential, but in reverse order, and counting from zero down (col 5 -> GPIO04, col6  -> GPIO03 and so on).
-            data |= ( port0 & 0x01 ) << 4; 
-            data |= ( port0 & 0x02 ) << 2; 
-            data |= ( port0 & 0x04 ); 
-            data |= ( port0 & 0x08 ) >> 2; 
-            data |= ( port0 & 0x10 ) >> 4; 
-
-            tca9555_status = I2C_STATUS_SUCCESS;
-        out:
-            i2c_stop();
-
-            return data;
+            tca9555_status = i2c_readReg(I2C_ADDR, IREGP0, port0, 1, I2C_TIMEOUT);
+            if (tca9555_status) {  // if there was an error
+                // do nothing
+                return 0;
+            } else {
+                uint8_t port0 = ports[0];
+                uint8_t port1 = ports[1];
+
+                // We read all the pins on GPIOA.
+                // The initial state was all ones and any depressed key at a given column for the currently selected row will have its bit flipped to zero.
+                // The return value is a row as represented in the generic matrix code were the rightmost bits represent the lower columns and zeroes represent non-depressed keys while ones represent depressed keys.
+                // the pins connected to eact columns are sequential, but in reverse order, and counting from zero down (col 5 -> GPIO04, col6  -> GPIO03 and so on).
+                data |= ( port0 & 0x01 ) << 4; 
+                data |= ( port0 & 0x02 ) << 2; 
+                data |= ( port0 & 0x04 ); 
+                data |= ( port0 & 0x08 ) >> 2; 
+                data |= ( port0 & 0x10 ) >> 4; 
+
+                tca9555_status = I2C_STATUS_SUCCESS;
+                return data;
+            }
         }
     }
 }
@@ -256,20 +244,13 @@ static void select_row(uint8_t row) {
                 case 4: port1 &= ~(1 << 0); break;
                 case 5: port1 &= ~(1 << 1); break;
                 case 6: port1 &= ~(1 << 2); break;
-                case 7: port1 &= ~(1 << 3); break;
+                case 7: port0 &= ~(1 << 5); break;
                 default:                    break;
             }
 
+            tca9555_status = i2c_writeReg(I2C_ADDR, OREGP1, port1, 2, I2C_TIMEOUT);
             // Select the desired row by writing a byte for the entire GPIOB bus where only the bit representing the row we want to select is a zero (write instruction) and every other bit is a one.
             // Note that the row - MATRIX_ROWS_PER_SIDE reflects the fact that being on the right hand, the columns are numbered from MATRIX_ROWS_PER_SIDE to MATRIX_ROWS, but the pins we want to write to are indexed from zero up on the GPIOB bus.
-            tca9555_status = i2c_start(I2C_ADDR_WRITE, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(OREGP1, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-            tca9555_status = i2c_write(port1, I2C_TIMEOUT);
-            if (tca9555_status) goto out;
-        out:
-            i2c_stop();
         }
     }
 }
diff --git a/keyboards/sx60/i2cmaster.h b/keyboards/sx60/i2cmaster.h
deleted file mode 100644
index 3917b9e6c..000000000
--- a/keyboards/sx60/i2cmaster.h
+++ /dev/null
@@ -1,178 +0,0 @@
-#ifndef _I2CMASTER_H
-#define _I2CMASTER_H   1
-/************************************************************************* 
-* Title:    C include file for the I2C master interface 
-*           (i2cmaster.S or twimaster.c)
-* Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
-* File:     $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $
-* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
-* Target:   any AVR device
-* Usage:    see Doxygen manual
-**************************************************************************/
-
-#ifdef DOXYGEN
-/**
- @defgroup pfleury_ic2master I2C Master library
- @code #include <i2cmaster.h> @endcode
-  
- @brief I2C (TWI) Master Software Library
-
- Basic routines for communicating with I2C slave devices. This single master 
- implementation is limited to one bus master on the I2C bus. 
-
- This I2c library is implemented as a compact assembler software implementation of the I2C protocol 
- which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).
- Since the API for these two implementations is exactly the same, an application can be linked either against the
- software I2C implementation or the hardware I2C implementation.
-
- Use 4.7k pull-up resistor on the SDA and SCL pin.
- 
- Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module 
- i2cmaster.S to your target when using the software I2C implementation ! 
- 
- Adjust the  CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.
-
- @note 
-    The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted 
-    to GNU assembler and AVR-GCC C call interface.
-    Replaced the incorrect quarter period delays found in AVR300 with 
-    half period delays. 
-    
- @author Peter Fleury pfleury@gmx.ch  http://jump.to/fleury
-
- @par API Usage Example
-  The following code shows typical usage of this library, see example test_i2cmaster.c
-
- @code
-
- #include <i2cmaster.h>
-
-
- #define Dev24C02  0xA2      // device address of EEPROM 24C02, see datasheet
-
- int main(void)
- {
-     unsigned char ret;
-
-     i2c_init();                             // initialize I2C library
-
-     // write 0x75 to EEPROM address 5 (Byte Write) 
-     i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
-     i2c_write(0x05);                        // write address = 5
-     i2c_write(0x75);                        // write value 0x75 to EEPROM
-     i2c_stop();                             // set stop conditon = release bus
-
-
-     // read previously written value back from EEPROM address 5 
-     i2c_start_wait(Dev24C02+I2C_WRITE);     // set device address and write mode
-
-     i2c_write(0x05);                        // write address = 5
-     i2c_rep_start(Dev24C02+I2C_READ);       // set device address and read mode
-
-     ret = i2c_readNak();                    // read one byte from EEPROM
-     i2c_stop();
-
-     for(;;);
- }
- @endcode
-
-*/
-#endif /* DOXYGEN */
-
-/**@{*/
-
-#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
-#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
-#endif
-
-#include <avr/io.h>
-
-/** defines the data direction (reading from I2C device) in i2c_start(),i2c_rep_start() */
-#define I2C_READ    1
-
-/** defines the data direction (writing to I2C device) in i2c_start(),i2c_rep_start() */
-#define I2C_WRITE   0
-
-
-/**
- @brief initialize the I2C master interace. Need to be called only once 
- @param  void
- @return none
- */
-extern void i2c_init(void);
-
-
-/** 
- @brief Terminates the data transfer and releases the I2C bus 
- @param void
- @return none
- */
-extern void i2c_stop(void);
-
-
-/** 
- @brief Issues a start condition and sends address and transfer direction 
-  
- @param    addr address and transfer direction of I2C device
- @retval   0   device accessible 
- @retval   1   failed to access device 
- */
-extern unsigned char i2c_start(unsigned char addr);
-
-
-/**
- @brief Issues a repeated start condition and sends address and transfer direction 
-
- @param   addr address and transfer direction of I2C device
- @retval  0 device accessible
- @retval  1 failed to access device
- */
-extern unsigned char i2c_rep_start(unsigned char addr);
-
-
-/**
- @brief Issues a start condition and sends address and transfer direction 
-   
- If device is busy, use ack polling to wait until device ready 
- @param    addr address and transfer direction of I2C device
- @return   none
- */
-extern void i2c_start_wait(unsigned char addr);
-
- 
-/**
- @brief Send one byte to I2C device
- @param    data  byte to be transfered
- @retval   0 write successful
- @retval   1 write failed
- */
-extern unsigned char i2c_write(unsigned char data);
-
-
-/**
- @brief    read one byte from the I2C device, request more data from device 
- @return   byte read from I2C device
- */
-extern unsigned char i2c_readAck(void);
-
-/**
- @brief    read one byte from the I2C device, read is followed by a stop condition 
- @return   byte read from I2C device
- */
-extern unsigned char i2c_readNak(void);
-
-/** 
- @brief    read one byte from the I2C device
- 
- Implemented as a macro, which calls either i2c_readAck or i2c_readNak
- 
- @param    ack 1 send ack, request more data from device<br>
-               0 send nak, read is followed by a stop condition 
- @return   byte read from I2C device
- */
-extern unsigned char i2c_read(unsigned char ack);
-#define i2c_read(ack)  (ack) ? i2c_readAck() : i2c_readNak(); 
-
-
-/**@}*/
-#endif
diff --git a/keyboards/sx60/matrix.c b/keyboards/sx60/matrix.c
index 6fa0dd145..b7dc25425 100644
--- a/keyboards/sx60/matrix.c
+++ b/keyboards/sx60/matrix.c
@@ -243,15 +243,11 @@ static bool read_cols_on_row(matrix_row_t current_matrix[], uint8_t current_row)
         /* if there was an error */
         return 0;
     } else {
-        uint16_t data = 0;
-        mcp23018_status = i2c_start(I2C_ADDR_WRITE);    if (mcp23018_status) goto out;
-        mcp23018_status = i2c_write(GPIOA);             if (mcp23018_status) goto out;
-        mcp23018_status = i2c_start(I2C_ADDR_READ);     if (mcp23018_status) goto out;
-        data = i2c_readNak();
-        data = ~data;
-    out:
-        i2c_stop();
-        current_matrix[current_row] |= (data << 8);
+        uint8_t data = 0;
+        mcp23018_status = i2c_readReg(I2C_ADDR, GPIOA, &data, 1, I2C_TIMEOUT);
+        if (!mcp23018_status) {
+            current_matrix[current_row] |= (~((uint16_t)data) << 8);
+        }
     }
 
     /* For each col... */
@@ -278,11 +274,8 @@ static void select_row(uint8_t row)
         /* set active row low  : 0
            set active row output : 1
            set other rows hi-Z : 1 */
-        mcp23018_status = i2c_start(I2C_ADDR_WRITE);   if (mcp23018_status) goto out;
-        mcp23018_status = i2c_write(GPIOB);            if (mcp23018_status) goto out;
-        mcp23018_status = i2c_write(0xFF & ~(1<<abs(row-4))); if (mcp23018_status) goto out;
-    out:
-        i2c_stop();
+        uint8_t port = 0xFF & ~(1<<abs(row-4));
+        mcp23018_status = i2c_writeReg(I2C_ADDR, GPIOB, &port, 1, I2C_TIMEOUT);
     }
 
     uint8_t pin = row_pins[row];
diff --git a/keyboards/sx60/rules.mk b/keyboards/sx60/rules.mk
index 8c2ad5259..1550b65c1 100755
--- a/keyboards/sx60/rules.mk
+++ b/keyboards/sx60/rules.mk
@@ -27,5 +27,5 @@ RGBLIGHT_ENABLE = no
 CUSTOM_MATRIX = yes
 
 # project specific files
-SRC =  twimaster.c \
-  matrix.c
+QUANTUM_LIB_SRC += i2c_master.c
+SRC += matrix.c
diff --git a/keyboards/sx60/sx60.c b/keyboards/sx60/sx60.c
index ede8c07e9..cb7f2b88f 100755
--- a/keyboards/sx60/sx60.c
+++ b/keyboards/sx60/sx60.c
@@ -1,5 +1,5 @@
 #include "sx60.h"
-#include "i2cmaster.h"
+#include "i2c_master.h"
 
 
 bool i2c_initialized = 0;
@@ -18,21 +18,18 @@ uint8_t init_mcp23018(void) {
 
     /* B Pins are Row, A pins are Columns 
        Set them to output */
-    mcp23018_status = i2c_start(I2C_ADDR_WRITE);    if (mcp23018_status) goto out;
-    mcp23018_status = i2c_write(IODIRA);            if (mcp23018_status) goto out;
-    mcp23018_status = i2c_write(0b11111111);        if (mcp23018_status) goto out;
-    /* Now write to IODIRB */
-    mcp23018_status = i2c_write(0b00000000);        if (mcp23018_status) goto out;
-    i2c_stop();
-
-    mcp23018_status = i2c_start(I2C_ADDR_WRITE);    if (mcp23018_status) goto out;
-    mcp23018_status = i2c_write(GPPUA);             if (mcp23018_status) goto out;
-    mcp23018_status = i2c_write(0b11111111);        if (mcp23018_status) goto out;
-    /* Now write to GPPUB */
-    mcp23018_status = i2c_write(0b00000000);        if (mcp23018_status) goto out;
-
-out:
-    i2c_stop();
-
+    static uint8_t direction[2] = {
+        0b11111111,
+        0b00000000,
+    };
+    static uint8_t pullup[2] = {
+        0b11111111,
+        0b00000000,
+    };
+
+    mcp23018_status = i2c_writeReg(I2C_ADDR, IODIRA, direction, 2, I2C_TIMEOUT);
+    if (mcp23018_status) return mcp23018_status;
+
+    mcp23018_status = i2c_writeReg(I2C_ADDR, GPPUA, pullup, 2, I2C_TIMEOUT);
     return mcp23018_status;
 }
diff --git a/keyboards/sx60/sx60.h b/keyboards/sx60/sx60.h
index b9575c118..2c0aa8240 100755
--- a/keyboards/sx60/sx60.h
+++ b/keyboards/sx60/sx60.h
@@ -3,13 +3,12 @@
 #include "quantum.h"
 #include <stdint.h>
 #include <stdbool.h>
-#include "i2cmaster.h"
+#include "i2c_master.h"
 #include <util/delay.h>
 
 /* I2C aliases and register addresses (see "mcp23018.md") */
 #define I2C_ADDR        0b0100000
-#define I2C_ADDR_WRITE  ( (I2C_ADDR<<1) | I2C_WRITE )
-#define I2C_ADDR_READ   ( (I2C_ADDR<<1) | I2C_READ  )
+#define I2C_TIMEOUT     100
 #define IODIRA          0x00            /* i/o direction register */
 #define IODIRB          0x01
 #define GPPUA           0x0C            /* GPIO pull-up resistor register */
diff --git a/keyboards/sx60/twimaster.c b/keyboards/sx60/twimaster.c
deleted file mode 100644
index 30d8c24bf..000000000
--- a/keyboards/sx60/twimaster.c
+++ /dev/null
@@ -1,207 +0,0 @@
-/*************************************************************************
-* Title:    I2C master library using hardware TWI interface
-* Author:   Peter Fleury <pfleury@gmx.ch>  http://jump.to/fleury
-* File:     $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $
-* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
-* Target:   any AVR device with hardware TWI
-* Usage:    API compatible with I2C Software Library i2cmaster.h
-**************************************************************************/
-#include <inttypes.h>
-#include <compat/twi.h>
-
-#include <i2cmaster.h>
-
-/* define CPU frequency in Hz here if not defined in Makefile */
-#ifndef F_CPU
-#define F_CPU 16000000UL
-#endif
-
-/* I2C clock in Hz */
-#define SCL_CLOCK  400000L
-
-
-/*************************************************************************
- Initialization of the I2C bus interface. Need to be called only once
-*************************************************************************/
-void i2c_init(void)
-{
-  /* initialize TWI clock
-   * minimal values in Bit Rate Register (TWBR) and minimal Prescaler
-   * bits in the TWI Status Register should give us maximal possible
-   * I2C bus speed - about 444 kHz
-   *
-   * for more details, see 20.5.2 in ATmega16/32 secification
-   */
-
-  TWSR = 0;     /* no prescaler */
-  TWBR = 10;    /* must be >= 10 for stable operation */
-
-}/* i2c_init */
-
-
-/*************************************************************************
-  Issues a start condition and sends address and transfer direction.
-  return 0 = device accessible, 1= failed to access device
-*************************************************************************/
-unsigned char i2c_start(unsigned char address)
-{
-    uint8_t   twst;
-
-  /* send START condition */
-  TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
- 
-  /* wait until transmission completed */
-  while(!(TWCR & (1<<TWINT)));
-
-  /* check value of TWI Status Register. Mask prescaler bits. */
-  twst = TW_STATUS & 0xF8;
-  if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;
-
-  /* send device address */
-  TWDR = address;
-  TWCR = (1<<TWINT) | (1<<TWEN);
-
-  /* wail until transmission completed and ACK/NACK has been received */
-  while(!(TWCR & (1<<TWINT)));
-
-  /* check value of TWI Status Register. Mask prescaler bits. */
-  twst = TW_STATUS & 0xF8;
-  if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
-
-  return 0;
-
-}/* i2c_start */
-
-
-/*************************************************************************
- Issues a start condition and sends address and transfer direction.
- If device is busy, use ack polling to wait until device is ready
-
- Input:   address and transfer direction of I2C device
-*************************************************************************/
-void i2c_start_wait(unsigned char address)
-{
-    uint8_t   twst;
-
-
-    while ( 1 )
-    {
-      /* send START condition */
-      TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
-
-      /* wait until transmission completed */
-      while(!(TWCR & (1<<TWINT)));
-
-      /* check value of TWI Status Register. Mask prescaler bits. */
-      twst = TW_STATUS & 0xF8;
-      if ( (twst != TW_START) && (twst != TW_REP_START)) continue;
-
-      /* send device address */
-      TWDR = address;
-      TWCR = (1<<TWINT) | (1<<TWEN);
-
-      /* wail until transmission completed */
-      while(!(TWCR & (1<<TWINT)));
-
-      /* check value of TWI Status Register. Mask prescaler bits. */
-      twst = TW_STATUS & 0xF8;
-      if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) )
-      {
-          /* device busy, send stop condition to terminate write operation */
-          TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
-
-          /* wait until stop condition is executed and bus released */
-          while(TWCR & (1<<TWSTO));
-
-          continue;
-      }
-      
-      break;
-     }
-
-}/* i2c_start_wait */
-
-
-/*************************************************************************
- Issues a repeated start condition and sends address and transfer direction
-
- Input:   address and transfer direction of I2C device
-
- Return:  0 device accessible
-          1 failed to access device
-*************************************************************************/
-unsigned char i2c_rep_start(unsigned char address)
-{
-    return i2c_start( address );
-
-}/* i2c_rep_start */
-
-
-/*************************************************************************
- Terminates the data transfer and releases the I2C bus
-*************************************************************************/
-void i2c_stop(void)
-{
-  /* send stop condition */
-  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
-
-  /* wait until stop condition is executed and bus released */
-  while(TWCR & (1<<TWSTO));
-
-}/* i2c_stop */
-
-
-/*************************************************************************
-  Send one byte to I2C device
-
-  Input:    byte to be transfered
-  Return:   0 write successful
-            1 write failed
-*************************************************************************/
-unsigned char i2c_write( unsigned char data )
-{
-    uint8_t   twst;
-
-  /* send data to the previously addressed device */
-  TWDR = data;
-  TWCR = (1<<TWINT) | (1<<TWEN);
-
-  /* wait until transmission completed */
-  while(!(TWCR & (1<<TWINT)));
-
-  /* check value of TWI Status Register. Mask prescaler bits */
-  twst = TW_STATUS & 0xF8;
-  if( twst != TW_MT_DATA_ACK) return 1;
-  return 0;
-
-}/* i2c_write */
-
-
-/*************************************************************************
- Read one byte from the I2C device, request more data from device
-
- Return:  byte read from I2C device
-*************************************************************************/
-unsigned char i2c_readAck(void)
-{
-  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
-  while(!(TWCR & (1<<TWINT)));
-
-  return TWDR;
-
-}/* i2c_readAck */
-
-
-/*************************************************************************
- Read one byte from the I2C device, read is followed by a stop condition
-
- Return:  byte read from I2C device
-*************************************************************************/
-unsigned char i2c_readNak(void)
-{
-  TWCR = (1<<TWINT) | (1<<TWEN);
-  while(!(TWCR & (1<<TWINT)));
-
-  return TWDR;
-
-}/* i2c_readNak */