112 lines
2.7 KiB
C
112 lines
2.7 KiB
C
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#include "mma8653.h"
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#include <util/twi.h>
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#define AXL_ADDR 0x1D
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#define AXL_ERR_RET(e) if(1){err = e; goto err;}
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#define TRY(c) if(1){ret = c; if (ret) return c;}
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static int mma8653_i2c_transfer(int write, uint8_t reg, uint8_t *data, uint8_t length)
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{
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int err = 0;
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// WRITE TARGET REGISTER
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// Send start
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TWCR = (1<<TWINT) | (1<<TWSTA) | (1 << TWEN);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != TW_START)
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AXL_ERR_RET(1);
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// Send device address
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TWDR = (AXL_ADDR << 1);
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TWCR = (1<<TWINT) | (1<<TWEN);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != TW_MT_SLA_ACK)
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AXL_ERR_RET(2);
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// Write register address
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TWDR = reg;
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TWCR = (1<<TWINT) | (1<<TWEN);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != TW_MT_DATA_ACK)
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AXL_ERR_RET(3);
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if (!write) {
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// Get data
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// Send re-start
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TWCR = (1<<TWINT) | (1<<TWSTA) | (1 << TWEN);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != TW_REP_START)
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AXL_ERR_RET(4);
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// Command a read cycle
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TWDR = (AXL_ADDR << 1) | (!write);
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TWCR = (1<<TWINT) | (1<<TWEN);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != (write ? TW_MT_SLA_ACK : TW_MR_SLA_ACK))
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AXL_ERR_RET(5);
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}
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while (length--) {
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if (write) {
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TWDR = *(data++);
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TWCR = (1<<TWINT) | (1<<TWEN);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != TW_MT_DATA_ACK)
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AXL_ERR_RET(6);
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} else {
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// Read byte
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TWCR = (1<<TWINT) | (1<<TWEN) | ( (length != 0) << TWEA);
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while (!(TWCR & (1<<TWINT)));
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if ((TWSR & 0xF8) != (length != 0 ? TW_MR_DATA_ACK : TW_MR_DATA_NACK))
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AXL_ERR_RET(6);
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*(data++) = TWDR;
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}
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}
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// Send stop
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TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
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while (TWCR & (1<<TWSTO));
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return 0;
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err:
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TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO); // Send stop to abort
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return err;
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}
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static inline int mma8653_i2c_write(uint8_t reg, uint8_t value)
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{
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return mma8653_i2c_transfer(1, reg, &value, 1);
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}
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int mma8653_init() {
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int ret;
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TWBR = 0xff;
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//TWSR = 3;
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TRY(mma8653_i2c_write(0x2A, (1 << 1) | (1 << 0)));
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TRY(mma8653_i2c_write(0x2B, (1 << 7))); // Test mode en
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return 0;
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}
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int mma8653_get_measurements(struct axl_result *measurements) {
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int ret;
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int8_t buffer[4];
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TRY(mma8653_i2c_transfer(0, 0x0, (uint8_t*) buffer, 4));
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measurements->x = buffer[1];
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measurements->y = buffer[2];
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measurements->z = buffer[3];
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/*
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led[0].r = buffer[1] > 0;
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led[1].r = buffer[2] > 0;
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led[2].r = buffer[3] > 0;
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led[5].r = !!(buffer[0] & 1); // 0
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led[5].g = !!(buffer[0] & 2); // 1
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led[5].b = !!(buffer[0] & 4); // 2
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led[4].r = !!(buffer[0] & 8); // 3
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led[4].g = !!(buffer[0] & 16); // 4
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led[4].b = !!(buffer[0] & 32); // 5
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led[3].r = !!(buffer[0] & 64); // 6
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led[3].g = !!(buffer[0] & 128); // 7
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*/
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return 0;
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}
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