diff options
Diffstat (limited to 'src/arch/arduino-nano/driver')
| -rw-r--r-- | src/arch/arduino-nano/driver/i2c.cc | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/src/arch/arduino-nano/driver/i2c.cc b/src/arch/arduino-nano/driver/i2c.cc index a644ca9..cfbea59 100644 --- a/src/arch/arduino-nano/driver/i2c.cc +++ b/src/arch/arduino-nano/driver/i2c.cc @@ -1,5 +1,15 @@ #include "driver/i2c.h" +#include "arch.h" #include <avr/io.h> +#include <avr/interrupt.h> + +inline void await_twint(unsigned char twcr_values) +{ + TWCR = twcr_values | _BV(TWINT) | _BV(TWIE); + while (!(TWCR & _BV(TWINT))) { + arch.idle(); + } +} /* * Send an I2C (re)start condition and the EEPROM address in read mode. Returns @@ -7,16 +17,14 @@ */ static signed char i2c_start_read(unsigned char addr) { - TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN); - while (!(TWCR & _BV(TWINT))); + await_twint(_BV(TWSTA) | _BV(TWEN)); if (!(TWSR & 0x18)) // 0x08 == START ok, 0x10 == RESTART ok return -1; // Note: The R byte ("... | 1") causes the TWI momodule to switch to // Master Receive mode TWDR = (addr << 1) | 1; - TWCR = _BV(TWINT) | _BV(TWEN); - while (!(TWCR & _BV(TWINT))); + await_twint(_BV(TWEN)); if (TWSR != 0x40) // 0x40 == SLA+R transmitted, ACK receveid return -2; @@ -29,14 +37,12 @@ static signed char i2c_start_read(unsigned char addr) */ static signed char i2c_start_write(unsigned char addr) { - TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN); - while (!(TWCR & _BV(TWINT))); + await_twint(_BV(TWSTA) | _BV(TWEN)); if (!(TWSR & 0x18)) // 0x08 == START ok, 0x10 == RESTART ok return -1; TWDR = (addr<< 1) | 0; - TWCR = _BV(TWINT) | _BV(TWEN); - while (!(TWCR & _BV(TWINT))); + await_twint(_BV(TWEN)); if (TWSR != 0x18) // 0x18 == SLA+W transmitted, ACK received return -2; @@ -61,8 +67,7 @@ static signed char i2c_send(uint8_t len, uint8_t *data) for (pos = 0; pos < len; pos++) { TWDR = data[pos]; - TWCR = _BV(TWINT) | _BV(TWEN); - while (!(TWCR & _BV(TWINT))); + await_twint(_BV(TWEN)); if (TWSR != 0x28) // 0x28 == byte transmitted, ACK received return pos; } @@ -79,14 +84,7 @@ static signed char i2c_receive(uint8_t len, uint8_t *data) uint8_t pos = 0; for (pos = 0; pos < len; pos++) { - if (pos == len-1) { - // Don't ACK the last byte - TWCR = _BV(TWINT) | _BV(TWEN); - } else { - // Automatically send ACK - TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA); - } - while (!(TWCR & _BV(TWINT))); + await_twint(_BV(TWEN) | ( _BV(TWEA) * (pos < len-1) ) ); data[pos] = TWDR; /* * No error handling here -- We send the acks, the EEPROM only @@ -111,6 +109,7 @@ void I2C::scan(unsigned int *results) for (unsigned char address = 0; address < 128; address++) { if (i2c_start_read(address) == 0) { results[address / (8 * sizeof(unsigned int))] |= 1 << (address % (8 * sizeof(unsigned int))); + i2c_stop(); } } i2c_stop(); @@ -144,3 +143,7 @@ signed char I2C::xmit(unsigned char address, } I2C i2c; + +ISR(TWI_vect) +{ +} |