From 7b2f6fc02881ec6a01a3b1d4ae248202232c4c6c Mon Sep 17 00:00:00 2001 From: Paolo Paolucci Date: Mon, 7 Mar 2016 18:40:09 +0100 Subject: Fix Wire register Move TWBR register from Wire.cpp to twi.c file. --- libraries/Wire/src/utility/twi.c | 16 ++++++++++++++++ libraries/Wire/src/utility/twi.h | 1 + 2 files changed, 17 insertions(+) (limited to 'libraries/Wire/src/utility') diff --git a/libraries/Wire/src/utility/twi.c b/libraries/Wire/src/utility/twi.c index 7efcc5a..f5d7d5b 100644 --- a/libraries/Wire/src/utility/twi.c +++ b/libraries/Wire/src/utility/twi.c @@ -118,6 +118,22 @@ void twi_setAddress(uint8_t address) TWAR = address << 1; } +/* + * 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 diff --git a/libraries/Wire/src/utility/twi.h b/libraries/Wire/src/utility/twi.h index 4c52bc5..d27325e 100644 --- a/libraries/Wire/src/utility/twi.h +++ b/libraries/Wire/src/utility/twi.h @@ -41,6 +41,7 @@ void twi_init(void); void twi_disable(void); void twi_setAddress(uint8_t); + void twi_setFrequency(uint32_t); uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t, uint8_t); uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t, uint8_t); uint8_t twi_transmit(const uint8_t*, uint8_t); -- cgit v1.2.3-18-g5258