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[/] [neo430/] [trunk/] [neo430/] [sw/] [lib/] [neo430/] [source/] [neo430_twi.c] - Rev 198
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// ################################################################################################# // # < neo430_twi.c - Internal Two Wire Serial interface functions > # // # ********************************************************************************************* # // # BSD 3-Clause License # // # # // # Copyright (c) 2020, Stephan Nolting. All rights reserved. # // # # // # Redistribution and use in source and binary forms, with or without modification, are # // # permitted provided that the following conditions are met: # // # # // # 1. Redistributions of source code must retain the above copyright notice, this list of # // # conditions and the following disclaimer. # // # # // # 2. 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. # // # # // # 3. Neither the name of the copyright holder 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 HOLDER 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. # // # ********************************************************************************************* # // # The NEO430 Processor - https://github.com/stnolting/neo430 # // ################################################################################################# #include "neo430.h" #include "neo430_twi.h" /* ------------------------------------------------------------ * INFO Activate (and reset) TWI module * PARAM clock prescaler * ------------------------------------------------------------ */ void neo430_twi_enable(uint8_t prsc) { TWI_CT = 0; // reset TWI_CT = (1 << TWI_CT_EN) | (prsc << TWI_CT_PRSC0); } /* ------------------------------------------------------------ * INFO Deactivate TWI module * ------------------------------------------------------------ */ void neo430_twi_disable(void) { TWI_CT = 0; } /* ------------------------------------------------------------ * INFO Activate sending ACK by master after transmission * ------------------------------------------------------------ */ void neo430_twi_mack_enable(void) { TWI_CT |= (1 << TWI_CT_MACK); } /* ------------------------------------------------------------ * INFO Deactivate sending ACK by master after transmission (normal mode) * ACK is sampled from slave * ------------------------------------------------------------ */ void neo430_twi_mack_disable(void) { TWI_CT &= ~(1 << TWI_CT_MACK); } /* ------------------------------------------------------------ * INFO Generate START condition and send first byte (address & R/W) * PARAM 8-bit including 7-bit address and read/write bit * RETURN 0 if ACK received, 1 if no valid ACK was received * ------------------------------------------------------------ */ uint8_t neo430_twi_start_trans(uint8_t a) { neo430_twi_generate_start(); // generate START condition TWI_DATA = (uint16_t)a; // send address while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again // check for ACK/NACK if (TWI_DATA & (1 << TWI_DT_ACK)) return 0; // ACK received else return 1; // NACK received } /* ------------------------------------------------------------ * INFO Send data and also sample input data * PARAM Data byte to be sent * RETURN 0 if ACK received, 1 if no valid ACK was received * ------------------------------------------------------------ */ uint8_t neo430_twi_trans(uint8_t d) { TWI_DATA = (uint16_t)d; // send data while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again // check for ACK/NACK if (TWI_DATA & (1 << TWI_DT_ACK)) return 0; // ACK received else return 1; // NACK received } /* ------------------------------------------------------------ * INFO Get rx data from previous transmission * RETURN Last received data byte * ------------------------------------------------------------ */ uint8_t neo430_twi_get_data(void) { return (uint8_t)TWI_DATA; // get RX data from previous transmission } /* ------------------------------------------------------------ * INFO Generate STOP condition * ------------------------------------------------------------ */ void neo430_twi_generate_stop(void) { TWI_CT |= (1 << TWI_CT_STOP); // generate STOP condition while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again } /* ------------------------------------------------------------ * INFO Generate START condition * ------------------------------------------------------------ */ void neo430_twi_generate_start(void) { TWI_CT |= (1 << TWI_CT_START); // generate START condition while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again }