Rename i2c_slave functions so it can coexist with i2c_master (#4875)

[qmk_firmware.git] / drivers / avr / i2c_slave.c

diff --git a/drivers/avr/i2c_slave.c b/drivers/avr/i2c_slave.c
index 3edf85b12b4da79c991cc4f48eff27c8c5c124d5..18a29a45a5a440433c6a7b8376c2ae4777734545 100755 (executable)
--- a/drivers/avr/i2c_slave.c
+++ b/drivers/avr/i2c_slave.c
@@ -5,96 +5,67 @@
 #include <avr/io.h>
 #include <util/twi.h>
 #include <avr/interrupt.h>
+#include <stdbool.h>
 
 #include "i2c_slave.h"
 
-void i2c_init(uint8_t address){
-       // load address into TWI address register
-       TWAR = (address << 1);
-       // set the TWCR to enable address matching and enable TWI, clear TWINT, enable TWI interrupt
-       TWCR = (1<<TWIE) | (1<<TWEA) | (1<<TWINT) | (1<<TWEN);
+volatile uint8_t i2c_slave_reg[I2C_SLAVE_REG_COUNT];
+
+static volatile uint8_t buffer_address;
+static volatile bool slave_has_register_set = false;
+
+void i2c_slave_init(uint8_t address){
+    // load address into TWI address register
+    TWAR = (address << 1);
+    // set the TWCR to enable address matching and enable TWI, clear TWINT, enable TWI interrupt
+    TWCR = (1 << TWIE) | (1 << TWEA) | (1 << TWINT) | (1 << TWEN);
 }
 
-void i2c_stop(void){
-       // clear acknowledge and enable bits
-       TWCR &= ~( (1<<TWEA) | (1<<TWEN) );
+void i2c_slave_stop(void){
+    // clear acknowledge and enable bits
+    TWCR &= ~((1 << TWEA) | (1 << TWEN));
 }
 
 ISR(TWI_vect){
-       
-       // temporary stores the received data
-       uint8_t data;
-       
-       // own address has been acknowledged
-       if( (TWSR & 0xF8) == TW_SR_SLA_ACK ){  
-               buffer_address = 0xFF;
-               // clear TWI interrupt flag, prepare to receive next byte and acknowledge
-               TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); 
-       }
-       else if( (TWSR & 0xF8) == TW_SR_DATA_ACK ){ // data has been received in slave receiver mode
-               
-               // save the received byte inside data 
-               data = TWDR;
-               
-               // check wether an address has already been transmitted or not
-               if(buffer_address == 0xFF){
-                       
-                       buffer_address = data; 
-                       
-                       // clear TWI interrupt flag, prepare to receive next byte and acknowledge
-                       TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); 
-               }
-               else{ // if a databyte has already been received
-                       
-                       // store the data at the current address
-                       rxbuffer[buffer_address] = data;
-                       
-                       // increment the buffer address
-                       buffer_address++;
-                       
-                       // if there is still enough space inside the buffer
-                       if(buffer_address < 0xFF){
-                               // clear TWI interrupt flag, prepare to receive next byte and acknowledge
-                               TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); 
-                       }
-                       else{
-                               // Don't acknowledge
-                               TWCR &= ~(1<<TWEA); 
-                               // clear TWI interrupt flag, prepare to receive last byte.
-                               TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEN); 
-                       }
-               }
-       }
-       else if( (TWSR & 0xF8) == TW_ST_DATA_ACK ){ // device has been addressed to be a transmitter
-               
-               // copy data from TWDR to the temporary memory
-               data = TWDR;
-               
-               // if no buffer read address has been sent yet
-               if( buffer_address == 0xFF ){
-                       buffer_address = data;
-               }
-               
-               // copy the specified buffer address into the TWDR register for transmission
-               TWDR = txbuffer[buffer_address];
-               // increment buffer read address
-               buffer_address++;
-               
-               // if there is another buffer address that can be sent
-               if(buffer_address < 0xFF){
-                       // clear TWI interrupt flag, prepare to send next byte and receive acknowledge
-                       TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEA) | (1<<TWEN); 
-               }
-               else{
-                       // Don't acknowledge
-                       TWCR &= ~(1<<TWEA); 
-                       // clear TWI interrupt flag, prepare to receive last byte.
-                       TWCR |= (1<<TWIE) | (1<<TWINT) | (1<<TWEN); 
-               }
-               
-       }
-       else{
-               // if none of the above apply prepare TWI to be addressed again
-               TWCR |= (1<<TWIE) | (1<<TWEA) | (1<<TWEN);
-       } 
-}
+    uint8_t ack = 1;
+
+    switch(TW_STATUS){
+        case TW_SR_SLA_ACK:
+            // The device is now a slave receiver
+            slave_has_register_set = false;
+            break;
+
+        case TW_SR_DATA_ACK:
+            // This device is a slave receiver and has received data
+            // First byte is the location then the bytes will be writen in buffer with auto-incriment
+            if(!slave_has_register_set){
+                buffer_address = TWDR;
+
+                if (buffer_address >= I2C_SLAVE_REG_COUNT) {  // address out of bounds dont ack
+                  ack            = 0;
+                  buffer_address = 0;
+                }
+                slave_has_register_set = true; // address has been receaved now fill in buffer
+            } else {
+                i2c_slave_reg[buffer_address] = TWDR;
+                buffer_address++;
+            }
+            break;
+
+        case TW_ST_SLA_ACK:
+        case TW_ST_DATA_ACK:
+            // This device is a slave transmitter and master has requested data
+            TWDR = i2c_slave_reg[buffer_address];
+            buffer_address++;
+            break;
+
+        case TW_BUS_ERROR:
+            // We got an error, reset i2c
+            TWCR = 0;
+        default:
+            break;
+    }
+
+    // Reset i2c state machine to be ready for next interrupt
+    TWCR |= (1 << TWIE) | (1 << TWINT) | (ack << TWEA) | (1 << TWEN);
+}
\ No newline at end of file