fj604 34 Posted June 2, 2011 Share Posted June 2, 2011 As promised here: http://www.43oh.com/forum/viewtopic.php?f=10&t=1015 MAX6956 is an I2C LED driver / port expander, here is a demo: /* * Interfacing MSP430G2231 to MAX6956 I2C LED driver and I/O expander Pins MSP430G2231 MAX6956 1 DVCC ----------- 28 V+ 8 P1.6/SCL ----------- 26 SCL 9 P1.7/SDA ----------- 25 SDA 14 DVSS ----------- 2 GND ----------- GND 3 GND ----------- GND 4 AD0 ----------- GND 27 AD1 ----------- GND 1 ISET -/\/39K\/\- GND 12 P19 ----------- LED1 13 P20 ----------- LED2 14 P21 ----------- LED3 8 P15 ----/ ----- GND Upon startup, LED1-3 will light up for about 1.5 seconds, then LED2-3 will start glowing intermittently. While a button on P15 is pushed, LED1 will change brightness. */ #include #define PIN_CS BIT1 #define PIN_SCL BIT6 #define PIN_SDA BIT7 #define DELAY 40000 #define MAX6956_ADDR 0x80 #define ACK 0x00 #define NACK 0xFF void i2c_init(void) { BCSCTL1 = CALBC1_1MHZ; // Set DCO DCOCTL = CALDCO_1MHZ; P1REN |= PIN_SCL | PIN_SDA; // Enable pullup resistors for I2C termination P1OUT |= PIN_SCL | PIN_SDA; USICTL0 = USIPE7 | USIPE6 | USIMST | USISWRST; // SDA enable, SCL enable, Master mode, release USICTL1 = USII2C | USIIE ; // USICKPH; // CKPH = 1, I2C, Interrupt Enable; USICKCTL = USIDIV_7 | USISSEL_2 | USICKPL; // Clock / 128, SMCLK, SCL inactive is high USICTL0 &= ~USISWRST; // Release from reset } void timer_init(void) { TACTL = TASSEL_2 | MC_0; // SMCLK, stop timer TACCTL0 = CCIE; // Enable timer compare interrupt } void sleep(unsigned int count) { TACCR0 = count; // Load top value in compare register TACTL |= TACLR | MC_1; // Clear counter, start timer in up mode _low_power_mode_0(); // Sleep in LPM0 until interrupt TACTL &= ~MC_1; // Stop timer } void i2c_tx_start(void) { USISRL = 0; USICTL0 |= USIGE | USIOE; // Latch enable, SDA enable USICTL0 &= ~USIGE; // Latch disable } void i2c_tx_stop(void) { USICTL0 |= USIOE; // SDA enable USISRL = 0; USICNT = 1; // Transmit 1 bit _low_power_mode_0(); // Sleep in LPM0 until interrupt USISRL = 0xFF; USICTL0 |= USIGE; // Latch enable USICTL0 &= ~(USIGE | USIOE); // Latch disable, SDA disable } unsigned char i2c_tx_byte(unsigned char byte) { USICTL0 |= USIOE; USISRL = byte; USICNT = 8; _low_power_mode_0(); // Sleep in LPM0 until interrupt USICTL0 &= ~USIOE; // SDA disable USICNT = 1; // Receive ACK bit _low_power_mode_0(); // Sleep in LPM0 until interrupt return USISRL & BIT0; // Return ACK = first bit of USISRL } unsigned char i2c_rx_byte(void) { unsigned char v; USICTL0 &= ~USIOE; USICNT = 8; _low_power_mode_0(); // Sleep in LPM0 until interrupt v = USISRL; return v; } void i2c_tx_ack(unsigned char ack) { USICTL0 |= USIOE; USISRL = ack; // Send ACK/NACK bit USICNT = 1; _low_power_mode_0(); // Sleep in LPM0 until interrupt } void max6956_send(unsigned char addr, unsigned char data) { i2c_tx_start(); i2c_tx_byte(MAX6956_ADDR); i2c_tx_byte(addr); i2c_tx_byte(data); i2c_tx_stop(); } unsigned char max6956_recv(unsigned char addr) { unsigned char v; i2c_tx_start(); i2c_tx_byte(MAX6956_ADDR); i2c_tx_byte(addr); i2c_tx_stop(); i2c_tx_start(); i2c_tx_byte(MAX6956_ADDR | BIT0); v = i2c_rx_byte(); // Read and send NACK to stop transmission i2c_tx_ack(NACK); i2c_tx_stop(); return v; } void sense(void) { static unsigned char g=0; if (!(max6956_recv(0x2F) & BIT0)) // Send No-op command and check bit 0 = button pushed max6956_send(0x19, g++ << 4); // Increase brightness of LED on port 19 } void leds(unsigned char v) { max6956_send(0x1A, v | (0x0F-v) << 4); // control brightness of LEDs on ports 20-21 sense(); } void main(void) { signed char i=0; WDTCTL = WDTPW + WDTHOLD; // Disable WDT i2c_init(); timer_init(); _enable_interrupts(); max6956_send(0x0C, 0x00); // set ports 16-19 to LED max6956_send(0x0D, 0x00); // set ports 20-23 to LED max6956_send(0x0B, 0xFF); // set ports 12-15 to GPIO Input with pullup max6956_send(0x33, 0x01); // Port 19 on max6956_send(0x34, 0x01); // Port 20 on max6956_send(0x35, 0x01); // Port 21 on max6956_send(0x07, 0x01); // Display test on _delay_cycles(1500000); // ~ 1.5s pause max6956_send(0x07, 0x00); // Display test off max6956_send(0x04, BIT0 | BIT6); // Individual segment current control, normal operation for (; { for (i=0; i<0x10; i++) { leds(i); sleep(DELAY); } for (i=0x0F; i>=0; i--) { leds(i); sleep(DELAY); } } } #pragma vector=USI_VECTOR __interrupt void usi_interrupt(void) { USICTL1 &= ~USIIFG; // Clear interrupt flag _low_power_mode_off_on_exit(); // Return from LPM } #pragma vector=TIMERA0_VECTOR __interrupt void timer_A_interrupt(void) { _low_power_mode_off_on_exit(); // Return from LPM } RobG, krzyk2, bluehash and 2 others 5 Quote Link to post Share on other sites
fj604 34 Posted June 3, 2011 Author Share Posted June 3, 2011 Here is a slightly modified version that implements a repeat start on I2C. It is explained here: http://e2e.ti.com/support/microcontrollers/msp43016-bit_ultra-low_power_mcus/f/166/t/105688.aspx /* * Interfacing MSP430G2231 to MAX6956 I2C LED driver and I/O expander Pins MSP430G2231 MAX6956 1 DVCC ----------- 28 V+ 8 P1.6/SCL ----------- 26 SCL 9 P1.7/SDA ----------- 25 SDA 14 DVSS ----------- 2 GND ----------- GND 3 GND ----------- GND 4 AD0 ----------- GND 27 AD1 ----------- GND 1 ISET -/\/39K\/\- GND 12 P19 ----------- LED1 13 P20 ----------- LED2 14 P21 ----------- LED3 8 P15 ----/ ----- GND Upon startup, LED1-3 will light up for about 1.5 seconds, then LED2-3 will start glowing intermittently. While a button on P15 is pushed, LED1 will change brightness. */ #include #define PIN_CS BIT1 #define PIN_SCL BIT6 #define PIN_SDA BIT7 #define DELAY 40000 #define MAX6956_ADDR 0x80 #define ACK 0x00 #define NACK 0xFF void i2c_init(void) { BCSCTL1 = CALBC1_1MHZ; // Set DCO DCOCTL = CALDCO_1MHZ; P1REN |= PIN_SCL | PIN_SDA; // Enable pullup resistors for I2C termination P1OUT |= PIN_SCL | PIN_SDA; USICTL0 = USIPE7 | USIPE6 | USIMST | USISWRST; // SDA enable, SCL enable, Master mode, release USICTL1 = USII2C | USIIE ; // USICKPH; // CKPH = 1, I2C, Interrupt Enable; USICKCTL = USIDIV_7 | USISSEL_2 | USICKPL; // Clock / 128, SMCLK, SCL inactive is high USICTL0 &= ~USISWRST; // Release from reset } void timer_init(void) { TACTL = TASSEL_2 | MC_0; // SMCLK, stop timer TACCTL0 = CCIE; // Enable timer compare interrupt } void sleep(unsigned int count) { TACCR0 = count; // Load top value in compare register TACTL |= TACLR | MC_1; // Clear counter, start timer in up mode _low_power_mode_0(); // Sleep in LPM0 until interrupt TACTL &= ~MC_1; // Stop timer } void i2c_tx_start(void) { USISRL = 0; USICTL0 |= USIGE | USIOE; // Latch enable, SDA enable USICTL0 &= ~USIGE; // Latch disable } void i2c_tx_rpt_start(void) { USICTL0 |= USIOE; // SDA enable USISRL = 0xFF; // Set MSB of USISRL to high USICNT = 1; // Transmit 1 bit for a surplus clock cycle _low_power_mode_0(); // Sleep in LPM0 until interrupt i2c_tx_start(); } void i2c_tx_stop(void) { USICTL0 |= USIOE; // SDA enable USISRL = 0; USICNT = 1; // Transmit 1 bit _low_power_mode_0(); // Sleep in LPM0 until interrupt USISRL = 0xFF; USICTL0 |= USIGE; // Latch enable USICTL0 &= ~(USIGE | USIOE); // Latch disable, SDA disable } unsigned char i2c_tx_byte(unsigned char byte) { USICTL0 |= USIOE; USISRL = byte; USICNT = 8; _low_power_mode_0(); // Sleep in LPM0 until interrupt USICTL0 &= ~USIOE; // SDA disable USICNT = 1; // Receive ACK bit _low_power_mode_0(); // Sleep in LPM0 until interrupt return USISRL & BIT0; // Return ACK = first bit of USISRL } unsigned char i2c_rx_byte(void) { unsigned char v; USICTL0 &= ~USIOE; USICNT = 8; _low_power_mode_0(); // Sleep in LPM0 until interrupt v = USISRL; return v; } void i2c_tx_ack(unsigned char ack) { USICTL0 |= USIOE; USISRL = ack; // Send ACK/NACK bit USICNT = 1; _low_power_mode_0(); // Sleep in LPM0 until interrupt } void max6956_send(unsigned char addr, unsigned char data) { i2c_tx_start(); i2c_tx_byte(MAX6956_ADDR); i2c_tx_byte(addr); i2c_tx_byte(data); i2c_tx_stop(); } unsigned char max6956_recv(unsigned char addr) { unsigned char v; i2c_tx_start(); i2c_tx_byte(MAX6956_ADDR); i2c_tx_byte(addr); i2c_tx_rpt_start(); // Generate a repeat start i2c_tx_byte(MAX6956_ADDR | BIT0); v = i2c_rx_byte(); // Read and send NACK to stop transmission i2c_tx_ack(NACK); i2c_tx_stop(); return v; } void sense(void) { static unsigned char g=0; if (!(max6956_recv(0x2F) & BIT0)) // Send No-op command and check bit 0 = button pushed max6956_send(0x19, g++ << 4); // Increase brightness of LED on port 19 } void leds(unsigned char v) { max6956_send(0x1A, v | (0x0F-v) << 4); // control brightness of LEDs on ports 20-21 sense(); } void main(void) { signed char i=0; WDTCTL = WDTPW + WDTHOLD; // Disable WDT i2c_init(); timer_init(); _enable_interrupts(); max6956_send(0x0C, 0x00); // set ports 16-19 to LED max6956_send(0x0D, 0x00); // set ports 20-23 to LED max6956_send(0x0B, 0xFF); // set ports 12-15 to GPIO Input with pullup max6956_send(0x33, 0x01); // Port 19 on max6956_send(0x34, 0x01); // Port 20 on max6956_send(0x35, 0x01); // Port 21 on max6956_send(0x07, 0x01); // Display test on _delay_cycles(1500000); // ~ 1.5s pause max6956_send(0x07, 0x00); // Display test off max6956_send(0x04, BIT0 | BIT6); // Individual segment current control, normal operation for (; { for (i=0; i<0x10; i++) { leds(i); sleep(DELAY); } for (i=0x0F; i>=0; i--) { leds(i); sleep(DELAY); } } } #pragma vector=USI_VECTOR __interrupt void usi_interrupt(void) { USICTL1 &= ~USIIFG; // Clear interrupt flag _low_power_mode_off_on_exit(); // Return from LPM } #pragma vector=TIMERA0_VECTOR __interrupt void timer_A_interrupt(void) { _low_power_mode_off_on_exit(); // Return from LPM } timotet and Simbo 2 Quote Link to post Share on other sites
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