/* --COPYRIGHT--,BSD_EX * Copyright (c) 2012, Texas Instruments Incorporated * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * * Neither the name of Texas Instruments Incorporated nor the names of * its contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ******************************************************************************* * * MSP430 CODE EXAMPLE DISCLAIMER * * MSP430 code examples are self-contained low-level programs that typically * demonstrate a single peripheral function or device feature in a highly * concise manner. For this the code may rely on the device's power-on default * register values and settings such as the clock configuration and care must * be taken when combining code from several examples to avoid potential side * effects. Also see www.ti.com/grace for a GUI- and www.ti.com/msp430ware * for an API functional library-approach to peripheral configuration. * * --/COPYRIGHT--*/ //****************************************************************************** // MSP430F20xx Demo - I2C Master Transmitter / Reciever, multiple bytes // // Description: I2C Master communicates with I2C Slave using // the USI. Master data should increment from 0x55 with each transmitted byte // and Master determines the number of bytes recieved, set by // the Number_of_Bytes value. LED off for address or data Ack; // LED on for address or data NAck. // ACLK = n/a, MCLK = SMCLK = Calibrated 1MHz // // // ***THIS IS THE MASTER CODE*** // // Slave Master // (msp430x20x3_usi_15.c) // MSP430F20x2/3 MSP430F20x2/3 // ----------------- ----------------- // /|\| XIN|- /|\| XIN|- // | | | | | | // --|RST XOUT|- --|RST XOUT|- // | | | | // LED <-|P1.0 | | | // | | | P1.0|-> LED // | SDA/P1.7|------->|P1.6/SDA | // | SCL/P1.6|<-------|P1.7/SCL | // // Note: internal pull-ups are used in this example for SDA & SCL // // R. B. Elliott / H. Grewal // Texas Instruments Inc. // February 2008 // Built with IAR Embedded Workbench Version: 3.42A //****************************************************************************** #include #define number_of_bytes 5 // How many bytes? void Master_Transmit(void); void Master_Recieve(void); void Setup_USI_Master_TX(void); void Setup_USI_Master_RX(void); char MST_Data = 0x55; // Variable for transmitted data char SLV_Addr = 0x90; int I2C_State, Bytecount, Transmit = 0; // State variable void Data_TX (void); void Data_RX (void); int main(void) { volatile unsigned int i; // Use volatile to prevent removal WDTCTL = WDTPW + WDTHOLD; // Stop watchdog 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 = 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; while(1) { Master_Transmit(); __no_operation(); // Used for IAR Master_Recieve(); __no_operation(); } } /****************************************************** // USI interrupt service routine // Data Transmit : state 0 -> 2 -> 4 -> 10 -> 12 -> 14 // Data Recieve : state 0 -> 2 -> 4 -> 6 -> 8 -> 14 ******************************************************/ #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 { switch(__even_in_range(I2C_State,14)) { case 0: // Generate Start Condition & send address to slave P1OUT |= 0x01; // LED on: sequence start Bytecount = 0; USISRL = 0x00; // Generate Start Condition... USICTL0 |= USIGE+USIOE; USICTL0 &= ~USIGE; if (Transmit == 1){ USISRL = 0x90; // Address is 0x48 << 1 bit + 0 (rw) } if (Transmit == 0){ USISRL = 0x91; // 0x91 Address is 0x48 << 1 bit // + 1 for Read } USICNT = (USICNT & 0xE0) + 0x08; // Bit counter = 8, TX Address I2C_State = 2; // next state: rcv 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 if(Transmit == 1){ 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 = 14; // Go to next state: generate Stop P1OUT |= 0x01; // Turn on LED: error } else { // Ack received, TX data to slave... USISRL = MST_Data++; // Load data byte USICNT |= 0x08; // Bit counter = 8, start TX I2C_State = 10; // next state: receive data (N)Ack Bytecount++; P1OUT &= ~0x01; // Turn off LED break; } } if(Transmit == 0){ if (USISRL & 0x01) // If Nack received { // Prep Stop Condition USICTL0 |= USIOE; USISRL = 0x00; USICNT |= 0x01; // Bit counter= 1, SCL high, SDA low I2C_State = 8; // Go to next state: generate Stop P1OUT |= 0x01; // Turn on LED: error } else{ Data_RX();} // Ack received } break; case 6: // Send Data Ack/Nack bit USICTL0 |= USIOE; // SDA = output if (Bytecount <= number_of_bytes-2) { // If this is not the last byte USISRL = 0x00; // Send Ack P1OUT &= ~0x01; // LED off I2C_State = 4; // Go to next state: data/rcv again Bytecount++; } else //last byte: send NACK { USISRL = 0xFF; // Send NAck P1OUT |= 0x01; // LED on: end of comm I2C_State = 8; // stop condition } USICNT |= 0x01; // Bit counter = 1, send (N)Ack bit break; case 8: // Prep Stop Condition USICTL0 |= USIOE; // SDA = output USISRL = 0x00; USICNT |= 0x01; // Bit counter= 1, SCL high, SDA low I2C_State = 14; // Go to next state: generate Stop break; case 10: // Receive Data Ack/Nack bit USICTL0 &= ~USIOE; // SDA = input USICNT |= 0x01; // Bit counter = 1, receive (N)Ack bit I2C_State = 12; // Go to next state: check (N)Ack break; case 12: // Process Data Ack/Nack & send Stop USICTL0 |= USIOE; if (Bytecount == number_of_bytes){// If last byte USISRL = 0x00; I2C_State = 14; // Go to next state: generate Stop P1OUT |= 0x01; USICNT |= 0x01; } // set count=1 to trigger next state else{ P1OUT &= ~0x01; // Turn off LED Data_TX(); // TX byte } break; case 14:// 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 xmt LPM0_EXIT; // Exit active for next transfer break; } USICTL1 &= ~USIIFG; // Clear pending flag } void Data_TX (void){ USISRL = MST_Data++; // Load data byte USICNT |= 0x08; // Bit counter = 8, start TX I2C_State = 10; // next state: receive data (N)Ack Bytecount++; } void Data_RX (void){ USICTL0 &= ~USIOE; // SDA = input --> redundant USICNT |= 0x08; // Bit counter = 8, RX data I2C_State = 6; // Next state: Test data and (N)Ack P1OUT &= ~0x01; // LED off } void Setup_USI_Master_TX (void) { __disable_interrupt(); Bytecount = 0; Transmit = 1; USICTL0 = USIPE6+USIPE7+USIMST+USISWRST; // Port & USI mode setup USICTL1 = USII2C+USIIE; // Enable I2C mode & USI interrupt USICKCTL = USIDIV_7+USISSEL_2+USICKPL; // USI clk: SCL = SMCLK/128 USICNT |= USIIFGCC; // Disable automatic clear control USICTL0 &= ~USISWRST; // Enable USI USICTL1 &= ~USIIFG; // Clear pending flag __enable_interrupt(); } void Setup_USI_Master_RX (void) { __disable_interrupt(); Bytecount = 0; Transmit = 0; USICTL0 = USIPE6+USIPE7+USIMST+USISWRST; // Port & USI mode setup USICTL1 = USII2C+USIIE; // Enable I2C mode & USI interrupt USICKCTL = USIDIV_7+USISSEL_2+USICKPL; // USI clks: SCL = SMCLK/128 USICNT |= USIIFGCC; // Disable automatic clear control USICTL0 &= ~USISWRST; // Enable USI USICTL1 &= ~USIIFG; // Clear pending flag __enable_interrupt(); } void Master_Transmit(void){ volatile unsigned int i; Setup_USI_Master_TX(); USICTL1 |= USIIFG; // Set flag and start communication LPM0; // CPU off, await USI interrupt for (i = 0; i < 5000; i++); // Delay between comm cycles } void Master_Recieve(void){ volatile unsigned int i; Setup_USI_Master_RX(); USICTL1 |= USIIFG; // Set flag and start communication LPM0; // CPU off, await USI interrupt for (i = 0; i < 5000; i++); // Delay between comm cycles }