diff options
Diffstat (limited to 'libraries/Wire/src/utility/twi.c')
-rw-r--r-- | libraries/Wire/src/utility/twi.c | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/libraries/Wire/src/utility/twi.c b/libraries/Wire/src/utility/twi.c index 7efcc5a..171af73 100644 --- a/libraries/Wire/src/utility/twi.c +++ b/libraries/Wire/src/utility/twi.c @@ -119,6 +119,22 @@ void twi_setAddress(uint8_t address) } /* + * Function twi_setClock + * Desc sets twi bit rate + * Input Clock Frequency + * Output none + */ +void twi_setFrequency(uint32_t frequency) +{ + TWBR = ((F_CPU / frequency) - 16) / 2; + + /* twi bit rate formula from atmega128 manual pg 204 + SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR)) + note: TWBR should be 10 or higher for master mode + It is 72 for a 16mhz Wiring board with 100kHz TWI */ +} + +/* * Function twi_readFrom * Desc attempts to become twi bus master and read a * series of bytes from a device on the bus @@ -288,7 +304,7 @@ uint8_t twi_transmit(const uint8_t* data, uint8_t length) uint8_t i; // ensure data will fit into buffer - if(TWI_BUFFER_LENGTH < length){ + if(TWI_BUFFER_LENGTH < (twi_txBufferLength+length)){ return 1; } @@ -298,10 +314,10 @@ uint8_t twi_transmit(const uint8_t* data, uint8_t length) } // set length and copy data into tx buffer - twi_txBufferLength = length; for(i = 0; i < length; ++i){ - twi_txBuffer[i] = data[i]; + twi_txBuffer[twi_txBufferLength+i] = data[i]; } + twi_txBufferLength += length; return 0; } |