From d707738616c140f8d9c8eded7b64e5fc806f4b24 Mon Sep 17 00:00:00 2001
From: Jack Humbert <jack.humb@gmail.com>
Date: Tue, 5 Jul 2016 23:27:10 -0400
Subject: i2c working

---
 keyboards/lets_split/i2c.c | 159 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 keyboards/lets_split/i2c.c

(limited to 'keyboards/lets_split/i2c.c')

diff --git a/keyboards/lets_split/i2c.c b/keyboards/lets_split/i2c.c
new file mode 100644
index 000000000..c72789403
--- /dev/null
+++ b/keyboards/lets_split/i2c.c
@@ -0,0 +1,159 @@
+#include <util/twi.h>
+#include <avr/io.h>
+#include <stdlib.h>
+#include <avr/interrupt.h>
+#include <util/twi.h>
+#include <stdbool.h>
+#include "i2c.h"
+
+// Limits the amount of we wait for any one i2c transaction.
+// Since were running SCL line 100kHz (=> 10μs/bit), and each transactions is
+// 9 bits, a single transaction will take around 90μs to complete.
+//
+// (F_CPU/SCL_CLOCK)  =>  # of μC cycles to transfer a bit
+// poll loop takes at least 8 clock cycles to execute
+#define I2C_LOOP_TIMEOUT (9+1)*(F_CPU/SCL_CLOCK)/8
+
+#define BUFFER_POS_INC() (slave_buffer_pos = (slave_buffer_pos+1)%SLAVE_BUFFER_SIZE)
+
+volatile uint8_t i2c_slave_buffer[SLAVE_BUFFER_SIZE];
+
+static volatile uint8_t slave_buffer_pos;
+static volatile bool slave_has_register_set = false;
+
+// Wait for an i2c operation to finish
+inline static
+void i2c_delay(void) {
+  uint16_t lim = 0;
+  while(!(TWCR & (1<<TWINT)) && lim < I2C_LOOP_TIMEOUT)
+    lim++;
+
+  // easier way, but will wait slightly longer
+  // _delay_us(100);
+}
+
+// Setup twi to run at 100kHz
+void i2c_master_init(void) {
+  // no prescaler
+  TWSR = 0;
+  // Set TWI clock frequency to SCL_CLOCK. Need TWBR>10.
+  // Check datasheets for more info.
+  TWBR = ((F_CPU/SCL_CLOCK)-16)/2;
+}
+
+// Start a transaction with the given i2c slave address. The direction of the
+// transfer is set with I2C_READ and I2C_WRITE.
+// returns: 0 => success
+//          1 => error
+uint8_t i2c_master_start(uint8_t address) {
+  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTA);
+
+  i2c_delay();
+
+  // check that we started successfully
+  if ( (TW_STATUS != TW_START) && (TW_STATUS != TW_REP_START))
+    return 1;
+
+  TWDR = address;
+  TWCR = (1<<TWINT) | (1<<TWEN);
+
+  i2c_delay();
+
+  if ( (TW_STATUS != TW_MT_SLA_ACK) && (TW_STATUS != TW_MR_SLA_ACK) )
+    return 1; // slave did not acknowledge
+  else
+    return 0; // success
+}
+
+
+// Finish the i2c transaction.
+void i2c_master_stop(void) {
+  TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+
+  uint16_t lim = 0;
+  while(!(TWCR & (1<<TWSTO)) && lim < I2C_LOOP_TIMEOUT)
+    lim++;
+}
+
+// Write one byte to the i2c slave.
+// returns 0 => slave ACK
+//         1 => slave NACK
+uint8_t i2c_master_write(uint8_t data) {
+  TWDR = data;
+  TWCR = (1<<TWINT) | (1<<TWEN);
+
+  i2c_delay();
+
+  // check if the slave acknowledged us
+  return (TW_STATUS == TW_MT_DATA_ACK) ? 0 : 1;
+}
+
+// Read one byte from the i2c slave. If ack=1 the slave is acknowledged,
+// if ack=0 the acknowledge bit is not set.
+// returns: byte read from i2c device
+uint8_t i2c_master_read(int ack) {
+  TWCR = (1<<TWINT) | (1<<TWEN) | (ack<<TWEA);
+
+  i2c_delay();
+  return TWDR;
+}
+
+void i2c_reset_state(void) {
+  TWCR = 0;
+}
+
+void i2c_slave_init(uint8_t address) {
+  TWAR = address << 0; // slave i2c address
+  // TWEN  - twi enable
+  // TWEA  - enable address acknowledgement
+  // TWINT - twi interrupt flag
+  // TWIE  - enable the twi interrupt
+  TWCR = (1<<TWIE) | (1<<TWEA) | (1<<TWINT) | (1<<TWEN);
+}
+
+ISR(TWI_vect);
+
+ISR(TWI_vect) {
+  uint8_t ack = 1;
+  switch(TW_STATUS) {
+    case TW_SR_SLA_ACK:
+      // this device has been addressed as a slave receiver
+      slave_has_register_set = false;
+      break;
+
+    case TW_SR_DATA_ACK:
+      // this device has received data as a slave receiver
+      // The first byte that we receive in this transaction sets the location
+      // of the read/write location of the slaves memory that it exposes over
+      // i2c.  After that, bytes will be written at slave_buffer_pos, incrementing
+      // slave_buffer_pos after each write.
+      if(!slave_has_register_set) {
+        slave_buffer_pos = TWDR;
+        // don't acknowledge the master if this memory loctaion is out of bounds
+        if ( slave_buffer_pos >= SLAVE_BUFFER_SIZE ) {
+          ack = 0;
+          slave_buffer_pos = 0;
+        }
+        slave_has_register_set = true;
+      } else {
+        i2c_slave_buffer[slave_buffer_pos] = TWDR;
+        BUFFER_POS_INC();
+      }
+      break;
+
+    case TW_ST_SLA_ACK:
+    case TW_ST_DATA_ACK:
+      // master has addressed this device as a slave transmitter and is
+      // requesting data.
+      TWDR = i2c_slave_buffer[slave_buffer_pos];
+      BUFFER_POS_INC();
+      break;
+
+    case TW_BUS_ERROR: // something went wrong, reset twi state
+      TWCR = 0;
+    default:
+      break;
+  }
+  // Reset everything, so we are ready for the next TWI interrupt
+  TWCR |= (1<<TWIE) | (1<<TWINT) | (ack<<TWEA) | (1<<TWEN);
+}
-- 
cgit v1.2.3-70-g09d2


From 6631abc1cb0e570271bcf33464e3af17b6fc0b87 Mon Sep 17 00:00:00 2001
From: IBNobody <ibnobody@gmail.com>
Date: Tue, 20 Sep 2016 21:38:59 -0500
Subject: Made Serial and I2C not include the Other

This saves 192 bytes
---
 keyboards/lets_split/config.h     |  7 ++++++-
 keyboards/lets_split/i2c.c        |  3 +++
 keyboards/lets_split/matrix.c     | 23 +++++++++++++++--------
 keyboards/lets_split/rules.mk     |  4 ++--
 keyboards/lets_split/serial.c     |  5 ++++-
 keyboards/lets_split/split_util.c |  8 ++++++--
 6 files changed, 36 insertions(+), 14 deletions(-)

(limited to 'keyboards/lets_split/i2c.c')

diff --git a/keyboards/lets_split/config.h b/keyboards/lets_split/config.h
index ec99514aa..f4d900acc 100644
--- a/keyboards/lets_split/config.h
+++ b/keyboards/lets_split/config.h
@@ -41,6 +41,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 // #define USE_I2C
 
+// Use serial if not using I2C
+#ifndef USE_I2C
+#  define USE_SERIAL
+#endif
+
 // #define EE_HANDS
 
 #define I2C_MASTER_LEFT
@@ -94,4 +99,4 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 //#define NO_ACTION_MACRO
 //#define NO_ACTION_FUNCTION
 
-#endif
\ No newline at end of file
+#endif
diff --git a/keyboards/lets_split/i2c.c b/keyboards/lets_split/i2c.c
index c72789403..084c890c4 100644
--- a/keyboards/lets_split/i2c.c
+++ b/keyboards/lets_split/i2c.c
@@ -6,6 +6,8 @@
 #include <stdbool.h>
 #include "i2c.h"
 
+#ifdef USE_I2C
+
 // Limits the amount of we wait for any one i2c transaction.
 // Since were running SCL line 100kHz (=> 10μs/bit), and each transactions is
 // 9 bits, a single transaction will take around 90μs to complete.
@@ -157,3 +159,4 @@ ISR(TWI_vect) {
   // Reset everything, so we are ready for the next TWI interrupt
   TWCR |= (1<<TWIE) | (1<<TWINT) | (ack<<TWEA) | (1<<TWEN);
 }
+#endif
diff --git a/keyboards/lets_split/matrix.c b/keyboards/lets_split/matrix.c
index 1d768c59b..138969004 100644
--- a/keyboards/lets_split/matrix.c
+++ b/keyboards/lets_split/matrix.c
@@ -28,14 +28,18 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "debug.h"
 #include "util.h"
 #include "matrix.h"
-#include "i2c.h"
-#include "serial.h"
 #include "split_util.h"
 #include "pro_micro.h"
 #include "config.h"
 
+#ifdef USE_I2C
+#  include "i2c.h"
+#else // USE_SERIAL
+#  include "serial.h"
+#endif
+
 #ifndef DEBOUNCE
-#   define DEBOUNCE	5
+#  define DEBOUNCE	5
 #endif
 
 #define ERROR_DISCONNECT_COUNT 5
@@ -145,6 +149,8 @@ uint8_t _matrix_scan(void)
     return 1;
 }
 
+#ifdef USE_I2C
+
 // Get rows from other half over i2c
 int i2c_transaction(void) {
     int slaveOffset = (isLeftHand) ? (ROWS_PER_HAND) : 0;
@@ -176,7 +182,8 @@ i2c_error: // the cable is disconnceted, or something else went wrong
     return 0;
 }
 
-#ifndef USE_I2C
+#else // USE_SERIAL
+
 int serial_transaction(void) {
     int slaveOffset = (isLeftHand) ? (ROWS_PER_HAND) : 0;
 
@@ -199,7 +206,7 @@ uint8_t matrix_scan(void)
 
 #ifdef USE_I2C
     if( i2c_transaction() ) {
-#else
+#else // USE_SERIAL
     if( serial_transaction() ) {
 #endif
         // turn on the indicator led when halves are disconnected
@@ -235,7 +242,7 @@ void matrix_slave_scan(void) {
         /* i2c_slave_buffer[i] = matrix[offset+i]; */
         i2c_slave_buffer[i] = matrix[offset+i];
     }
-#else
+#else // USE_SERIAL
     for (int i = 0; i < ROWS_PER_HAND; ++i) {
         serial_slave_buffer[i] = matrix[offset+i];
     }
@@ -290,7 +297,7 @@ static void  init_cols(void)
 static matrix_row_t read_cols(void)
 {
     matrix_row_t result = 0;
-    for(int x = 0; x < MATRIX_COLS; x++) {     
+    for(int x = 0; x < MATRIX_COLS; x++) {
         result |= (_SFR_IO8(col_pins[x] >> 4) & _BV(col_pins[x] & 0xF)) ? 0 : (1 << x);
     }
     return result;
@@ -298,7 +305,7 @@ static matrix_row_t read_cols(void)
 
 static void unselect_rows(void)
 {
-    for(int x = 0; x < ROWS_PER_HAND; x++) { 
+    for(int x = 0; x < ROWS_PER_HAND; x++) {
         _SFR_IO8((row_pins[x] >> 4) + 1) &=  ~_BV(row_pins[x] & 0xF);
         _SFR_IO8((row_pins[x] >> 4) + 2) |= _BV(row_pins[x] & 0xF);
     }
diff --git a/keyboards/lets_split/rules.mk b/keyboards/lets_split/rules.mk
index 6961fbd55..6fde8a444 100644
--- a/keyboards/lets_split/rules.mk
+++ b/keyboards/lets_split/rules.mk
@@ -52,7 +52,7 @@ OPT_DEFS += -DINTERRUPT_CONTROL_ENDPOINT
 OPT_DEFS += -DBOOTLOADER_SIZE=4096
 
 # Build Options
-#   change to "no" to disable the options, or define them in the Makefile in 
+#   change to "no" to disable the options, or define them in the Makefile in
 #   the appropriate keymap folder that will get included automatically
 #
 BOOTMAGIC_ENABLE ?= no       # Virtual DIP switch configuration(+1000)
@@ -71,4 +71,4 @@ RGBLIGHT_ENABLE ?= no        # Enable WS2812 RGB underlight.  Do not enable this
 # Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
 SLEEP_LED_ENABLE ?= no    # Breathing sleep LED during USB suspend
 
-CUSTOM_MATRIX = yes
\ No newline at end of file
+CUSTOM_MATRIX = yes
diff --git a/keyboards/lets_split/serial.c b/keyboards/lets_split/serial.c
index f439c2f20..6faed09ce 100644
--- a/keyboards/lets_split/serial.c
+++ b/keyboards/lets_split/serial.c
@@ -10,9 +10,10 @@
 #include <avr/interrupt.h>
 #include <util/delay.h>
 #include <stdbool.h>
-
 #include "serial.h"
 
+#ifdef USE_SERIAL
+
 // Serial pulse period in microseconds. Its probably a bad idea to lower this
 // value.
 #define SERIAL_DELAY 24
@@ -223,3 +224,5 @@ int serial_update_buffers(void) {
   sei();
   return 0;
 }
+
+#endif
diff --git a/keyboards/lets_split/split_util.c b/keyboards/lets_split/split_util.c
index 65003a71a..461921798 100644
--- a/keyboards/lets_split/split_util.c
+++ b/keyboards/lets_split/split_util.c
@@ -6,11 +6,15 @@
 #include <avr/eeprom.h>
 #include "split_util.h"
 #include "matrix.h"
-#include "i2c.h"
-#include "serial.h"
 #include "keyboard.h"
 #include "config.h"
 
+#ifdef USE_I2C
+#  include "i2c.h"
+#else
+#  include "serial.h"
+#endif
+
 volatile bool isLeftHand = true;
 
 static void setup_handedness(void) {
-- 
cgit v1.2.3-70-g09d2