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// #################################################################################################
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// # < neo430_twi.c - Internal Two Wire Serial interface functions > #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License #
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// # #
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// # Copyright (c) 2020, Stephan Nolting. All rights reserved. #
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// # #
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// # Redistribution and use in source and binary forms, with or without modification, are #
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// # permitted provided that the following conditions are met: #
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// # #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of #
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// # conditions and the following disclaimer. #
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// # #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
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// # conditions and the following disclaimer in the documentation and/or other materials #
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// # provided with the distribution. #
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// # #
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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
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// # endorse or promote products derived from this software without specific prior written #
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// # permission. #
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// # #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
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// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
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// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
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// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
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// # OF THE POSSIBILITY OF SUCH DAMAGE. #
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// # ********************************************************************************************* #
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// # The NEO430 Processor - https://github.com/stnolting/neo430 #
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// #################################################################################################
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#include "neo430.h"
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#include "neo430_twi.h"
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/* ------------------------------------------------------------
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* INFO Activate (and reset) TWI module
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* PARAM clock prescaler
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* ------------------------------------------------------------ */
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void neo430_twi_enable(uint8_t prsc) {
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TWI_CT = 0; // reset
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TWI_CT = (1 << TWI_CT_EN) | (prsc << TWI_CT_PRSC0);
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}
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/* ------------------------------------------------------------
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* INFO Deactivate TWI module
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* ------------------------------------------------------------ */
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void neo430_twi_disable(void) {
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TWI_CT = 0;
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}
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/* ------------------------------------------------------------
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* INFO Activate sending ACK by master after transmission
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* ------------------------------------------------------------ */
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void neo430_twi_mack_enable(void) {
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TWI_CT |= (1 << TWI_CT_MACK);
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}
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/* ------------------------------------------------------------
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* INFO Deactivate sending ACK by master after transmission (normal mode)
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* ACK is sampled from slave
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* ------------------------------------------------------------ */
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void neo430_twi_mack_disable(void) {
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TWI_CT &= ~(1 << TWI_CT_MACK);
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}
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/* ------------------------------------------------------------
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* INFO Generate START condition and send first byte (address & R/W)
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* PARAM 8-bit including 7-bit address and read/write bit
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* RETURN 0 if ACK received, 1 if no valid ACK was received
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* ------------------------------------------------------------ */
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uint8_t neo430_twi_start_trans(uint8_t a) {
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neo430_twi_generate_start(); // generate START condition
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TWI_DATA = (uint16_t)a; // send address
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while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again
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// check for ACK/NACK
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if (TWI_DATA & (1 << TWI_DT_ACK))
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return 0; // ACK received
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else
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return 1; // NACK received
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}
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/* ------------------------------------------------------------
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* INFO Send data and also sample input data
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* PARAM Data byte to be sent
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* RETURN 0 if ACK received, 1 if no valid ACK was received
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* ------------------------------------------------------------ */
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uint8_t neo430_twi_trans(uint8_t d) {
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TWI_DATA = (uint16_t)d; // send data
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while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again
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// check for ACK/NACK
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if (TWI_DATA & (1 << TWI_DT_ACK))
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return 0; // ACK received
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else
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return 1; // NACK received
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}
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/* ------------------------------------------------------------
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* INFO Get rx data from previous transmission
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* RETURN Last received data byte
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* ------------------------------------------------------------ */
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uint8_t neo430_twi_get_data(void) {
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return (uint8_t)TWI_DATA; // get RX data from previous transmission
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}
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/* ------------------------------------------------------------
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* INFO Generate STOP condition
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* ------------------------------------------------------------ */
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void neo430_twi_generate_stop(void) {
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TWI_CT |= (1 << TWI_CT_STOP); // generate STOP condition
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while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again
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}
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/* ------------------------------------------------------------
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* INFO Generate START condition
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* ------------------------------------------------------------ */
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void neo430_twi_generate_start(void) {
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TWI_CT |= (1 << TWI_CT_START); // generate START condition
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while(TWI_CT & (1 << TWI_CT_BUSY)); // wait until idle again
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}
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