Revision 797244ed
Get bom i2c start interrupt working
scout_avr/bom/tiny-twi.c | ||
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#include <util/delay.h> |
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#include "tiny-twi.h" |
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#define SDA PB0 |
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#define SCL PB2 |
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#define RECV_BUF_SIZE 2 |
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uint8_t address; |
... | ... | |
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slave_rx_t onDataRecieved; |
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static void twi_set_ctr(char n) { |
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USISR &= ~0x0F; |
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USISR |= n; |
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} |
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static void twi_release_scl() { |
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DDRB &= ~_BV(DDB2); |
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} |
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static void twi_sink_sda() { |
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DDRB |= _BV(DDB0); |
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} |
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static void twi_release_sda() { |
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DDRB &= ~_BV(DDB0); |
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USISR = n; |
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} |
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static void twi_ready() { |
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USISR = _BV(USISIF) | _BV(USIOIF) | _BV(USIPF) | _BV(USIDC); |
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DDRB |= _BV(SCL); //SCL output |
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DDRB &= ~_BV(SDA); //SDA input |
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// enable start condition interrupt |
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USICR |= _BV(USISIE); |
... | ... | |
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} |
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static void twi_start() { |
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// enable counter overflow interrupt (fires after 8 bits) |
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USICR |= _BV(USIOIE); |
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USISR = _BV(USISIF); |
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// zero counter |
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twi_set_ctr(0); |
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// enable counter overflow interrupt (fires after 8 bits) |
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USICR |= _BV(USIOIE); |
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state = ADDRESS; |
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recv_idx = 0; |
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} |
... | ... | |
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// set SDA low |
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USIDR = 0; |
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twi_sink_sda();
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DDRB |= _BV(SDA);
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// set state |
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state = is_read? SEND_READ_ACK : SEND_WRITE_ACK; |
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} |
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ISR(USI_START_vect) { |
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PORTB |= _BV(PB4); // DEBUG: LED ON |
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twi_start(); |
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} |
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|
... | ... | |
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break; |
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case SEND_WRITE_ACK: |
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twi_release_sda();
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DDRB &= ~_BV(SDA);
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state = RECV_DATA; |
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break; |
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|
... | ... | |
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break; |
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case SEND_READ_ACK: |
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twi_release_sda();
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DDRB &= ~_BV(SDA);
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// TODO write to USIDR |
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state = SEND_DATA; |
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break; |
... | ... | |
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case RECV_ACK: |
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break; |
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} |
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twi_release_scl();
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USISR = _BV(USIOIF) | (USISR & 0xF);
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} |
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void smb_init(slave_rx_t callback) { |
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// TODO do we want USICS0 (3)? |
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USICR = _BV(USIWM1) | _BV(USIWM0) | _BV(USICS1); |
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PORTB |= _BV(SDA) | _BV(SCL); |
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twi_ready(); |
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onDataRecieved = callback; |
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} |
... | ... | |
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int main() { |
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sei(); |
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smb_set_address(5); |
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DDRB |= _BV(DDB4); |
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smb_init(testCB); |
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} |
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while(1); |
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} |
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