MSP430 with ST7032i, now working!
After much fiddling, I got the ST7032i working with an MSP430. The fundamental issue seemed to be getting the I2C data formatting correct. The MSP430 doesn’t have hardware I2C support. What it does have is something called the USI (Universal Serial Interface?). This gives some hardware support for serial transfers, but start/stop/ack bits need to be handled in software. The issue was that the I2C examples provided by TI describe 8bit transfers. With each transfer the address is sent, followed by an ACK, followed by 8bits of data. The USI can also be configured to send 16bits in one go. However the ST7032i doesn’t do either of those things. And it was only after looking at the output of a working Arduino example, and from reading the ST7032i datasheet that I actually understood what was happening.
Basically the ST7032i expects I2C packets that looks like this:
[START][ADDRESS][ACK][DATA1][ACK][DATA2][ACK][STOP]
Such is my understanding a 3am anyway. And this format does appear to work. I’ve no idea if that’s normal for I2C 16bit comms, but certainly on the MSP430 you have to implement those ACKs in the middle of the data in software. For reference the board consumes ~0.5mA at 3.3V.
Current source code is below, complete working example (with header) is available on github. The code below should give some hint of how the process works however:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 | #include <msp430.h>#include "ST7032.h"unsigned short MST_Data1 = 0x40; // Variable for transmitted dataunsigned short MST_Data2 = 0x40; // Variable for transmitted datachar SLV_Addr = 0x7C; // Address is 0x48 << 1 bit + 0 for Writeint I2C_State = 0; // State variableint main(void){ volatile unsigned int i; // Use volatile to prevent removal WDTCTL = WDTPW + WDTHOLD; // Stop watchdog __delay_cycles(250000); if (CALBC1_1MHZ==0xFF) // If calibration constants erased { while(1); // do not load, trap CPU!! } DCOCTL = 0; // Select lowest DCOx and MODx settings BCSCTL1 = CALBC1_1MHZ; // Set DCO DCOCTL = CALDCO_1MHZ;// P1OUT = 0x0;// P1REN = 0x0; /////////////////////// P1SEL |= BIT6 + BIT7; // enable all pull up //P1OUT = 0xFF; // P1.6 & P1.7 Pullups, others to 0 //P1REN = 0xFF; // P1.6 & P1.7 Pullups P1OUT = 0xC0; // P1.6 & P1.7 Pullups, others to 0 P1REN |= 0xC0; // P1.6 & P1.7 Pullups P1DIR = 0xFF; // Unused pins as outputs P2OUT = 0; P2DIR = 0xFF; USICTL0 = USIPE6+USIPE7+USIMST+USISWRST; // Port & USI mode setup USICTL1 = USII2C+USIIE; // Enable I2C mode & USI interrupt //USICKCTL = USIDIV_3+USISSEL_2+USICKPL; // Setup USI clocks: SCL = SMCLK/8 (~125kHz) // was USIDIV_3 USICKCTL = USIDIV_3+USISSEL_2+USICKPL; // Setup USI clocks: SCL = SMCLK/8 (~125kHz) // was USIDIV_3 USICNT |= USIIFGCC; // Disable automatic clear control USICTL0 &= ~USISWRST; // Enable USI USICTL1 &= ~USIIFG; // Clear pending flag __enable_interrupt(); __delay_cycles(4000000); int a=0; int contrast = 0xff; for(int n=1;;n++) { unsigned char _displayfunction = LCD_8BITMODE | LCD_1LINE | LCD_5x8DOTS; _displayfunction |= LCD_2LINE; if(n==1) MST_Data1 = 0x00; if(n==1) MST_Data2 = LCD_FUNCTIONSET | _displayfunction; if(n==2) MST_Data1 = 0x00; if(n==2) MST_Data2 = LCD_FUNCTIONSET | _displayfunction | LCD_EX_INSTRUCTION; if(n==3) MST_Data1 = 0x00; if(n==3) MST_Data2 = LCD_EX_SETBIASOSC | LCD_BIAS_1_5 | LCD_OSC_183HZ; if(n==4) MST_Data1 = 0x00; if(n==4) MST_Data2 = LCD_EX_FOLLOWERCONTROL | LCD_FOLLOWER_ON | LCD_RAB_2_00; if(n==5) MST_Data1 = 0x00; if(n==5) MST_Data2 = LCD_FUNCTIONSET | _displayfunction; unsigned char _displaycontrol = LCD_DISPLAYON | LCD_CURSOROFF | LCD_BLINKOFF; if(n==6) MST_Data1 = 0x00; if(n==6) MST_Data2 = LCD_DISPLAYCONTROL | _displaycontrol; if(n==7) MST_Data1 = 0x00; if(n==7) MST_Data2 = LCD_CLEARDISPLAY; if(n==8) MST_Data1 = 0x00; if(n==8) MST_Data2 = LCD_ENTRYMODESET | LCD_ENTRYLEFT | LCD_ENTRYSHIFTDECREMENT; if(n==9) MST_Data1 = 0x00; if(n==9) MST_Data2 = LCD_FUNCTIONSET | _displayfunction | LCD_EX_INSTRUCTION; uint8_t cont = 20; if(n==10) MST_Data1 = 0x00; if(n==10) MST_Data2 = LCD_EX_CONTRASTSETL | (cont & 0x0f); if(n==11) MST_Data1 = 0x00; if(n==11) MST_Data2 = LCD_EX_POWICONCONTRASTH | LCD_ICON_ON | LCD_BOOST_ON | ((cont >> 4) & 0x03); if(n==12) MST_Data1 = 0x00; if(n==12) MST_Data2 = LCD_FUNCTIONSET | _displayfunction; if(n==13) MST_Data1 = (uint8_t) 0x40; if(n==13) MST_Data2 = 'H'; if(n==14) MST_Data1 = (uint8_t) 0x40; if(n==14) MST_Data2 = 'H'; if(n==15) MST_Data1 = (uint8_t) 0x40; if(n==15) MST_Data2 = (uint8_t) 'H'; if(n==16) MST_Data1 = (uint8_t) 0x40; if(n==16) MST_Data2 = 'H'; P1OUT |= 0x01; __delay_cycles(500); P1OUT &= ~0x01; // LED off USICTL1 |= USIIFG; // Set flag and start communication LPM0; // CPU off, await USI interrupt // while (!(USICTL1 & USIIFG));// busy wait __delay_cycles(1000000); if(n==4) {__delay_cycles(4000000); __delay_cycles(4000000);} if(n==7) {__delay_cycles(4000000); __delay_cycles(4000000);} if(n==32) {n=1;__delay_cycles(4000000); __delay_cycles(4000000); __delay_cycles(4000000);} }}/******************************************************// USI interrupt service routine******************************************************/#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)#pragma vector = USI_VECTOR__interrupt void USI_TXRX (void)#elif defined(__GNUC__)void __attribute__ ((interrupt(USI_VECTOR))) USI_TXRX (void)#else#error Compiler not supported!#endif{ //USICNT = USI16B | 16;//(USICNT & 0x0E) + 0x08; // Bit counter = 8, start TX switch(I2C_State) { case 0: // Generate Start Condition & send address to slave P1OUT &= ~0x01; // LED off USISRL = 0x00; // Generate Start Condition... USICTL0 |= USIGE+USIOE; USICTL0 &= ~USIGE; USISRL = SLV_Addr; // ... and transmit address, R/W = 0 USICNT = (USICNT & 0xE0) + 0x08; // Bit counter = 8, TX Address //USICNT = 0xE0 + 0x08; // Bit counter = 8, TX Address I2C_State = 2; // Go to next state: receive address (N)Ack break; case 2: // Receive Address Ack/Nack bit USICTL0 &= ~USIOE; // SDA = input USICNT |= 0x01; // Bit counter = 1, receive (N)Ack bit I2C_State = 4; // Go to next state: check (N)Ack break; case 4: // Process Address Ack/Nack & handle data TX USICTL0 |= USIOE; // SDA = output if (USISRL & 0x01) // If Nack received... { // Send stop... USISRL = 0x00; USICNT |= 0x01; // Bit counter = 1, SCL high, SDA low I2C_State = 10; // Go to next state: generate Stop // P1OUT |= 0x01; // Turn on LED: error P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); } else { // Ack received, TX data to slave... USISRL = MST_Data1; // Load data byte USICNT = (USICNT & 0x0E) + 0x08; // Bit counter = 8, start TX I2C_State = 41; // Go to next state: receive data (N)Ack } break; case 41: // Receive Data Ack/Nack bit USICTL0 &= ~USIOE; // SDA = input USICNT |= 0x01; // Bit counter = 1, receive (N)Ack bit I2C_State = 5; // Go to next state: check (N)Ack break; case 5: // Process Address Ack/Nack & handle data TX USICTL0 |= USIOE; // SDA = output if (USISRL & 0x01) // If Nack received... { // Send stop... USISRL = 0x00; USICNT |= 0x01; // Bit counter = 1, SCL high, SDA low I2C_State = 10; // Go to next state: generate Stop // P1OUT |= 0x01; // Turn on LED: error P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); } else { // Ack received, TX data to slave... USISRL = MST_Data2; // Load data byte USICNT = (USICNT & 0x0E) + 0x08; // Bit counter = 8, start TX I2C_State = 6; // Go to next state: receive data (N)Ack } break; case 6: // Receive Data Ack/Nack bit USICTL0 &= ~USIOE; // SDA = input USICNT |= 0x01; // Bit counter = 1, receive (N)Ack bit I2C_State = 8; // Go to next state: check (N)Ack break; case 8: // Process Data Ack/Nack & send Stop USICTL0 |= USIOE; if (USISRL & 0x01) { // If Nack received... P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); P1OUT |= 0x01; // Turn on LED: error __delay_cycles(500000); P1OUT &= ~0x01; // Turn on LED: error __delay_cycles(500000); } else // Ack received { // MST_Data++; // Increment Master data // P1OUT &= ~0x01; // Turn off LED } // Send stop... USISRL = 0x00; USICNT |= 0x01; // Bit counter = 1, SCL high, SDA low I2C_State = 10; // Go to next state: generate Stop break; case 10:// Generate Stop Condition USISRL = 0x0FF; // USISRL = 1 to release SDA USICTL0 |= USIGE; // Transparent latch enabled USICTL0 &= ~(USIGE+USIOE);// Latch/SDA output disabled I2C_State = 0; // Reset state machine for next transmission LPM0_EXIT; // Exit active for next transfer break; } USICTL1 &= ~USIIFG; // Clear pending flag} |
RSS