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bsec_iot_example/commMux.cpp

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+/**
+ Copyright (c) 2021 Bosch Sensortec GmbH. All rights reserved.
+
+ BSD-3-Clause
+
+ 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.
+
+ @file    commMux.cpp
+ @date    19 September 2022
+ @version 2.0.2
+
+ */
+
+#include "commMux.h"
+
+#define CLOCK_FREQUENCY 400000
+#define COMM_SPEED 8000000
+
+const uint8_t I2C_EXPANDER_ADDR = 0x20;
+const uint8_t I2C_EXPANDER_OUTPUT_REG_ADDR = 0x01;
+const uint8_t I2C_EXPANDER_OUTPUT_DESELECT = 0xFF;
+const uint8_t I2C_EXPANDER_CONFIG_REG_ADDR = 0x03;
+const uint8_t I2C_EXPANDER_CONFIG_REG_MASK = 0x00;
+
+/**
+ * @brief Function to configure the communication across sensors
+ */
+commMux commMuxSetConfig(TwoWire &wireobj, SPIClass &spiobj, uint8_t idx, commMux &comm)
+{
+	comm.select = ((0x01 << idx) ^ 0xFF);
+	comm.spiobj = &spiobj;
+	comm.wireobj = &wireobj;
+
+	return comm;
+}
+
+/**
+ * @brief Function to trigger the communication
+ */
+void commMuxBegin(TwoWire &wireobj, SPIClass &spiobj)
+{
+	wireobj.begin();
+	wireobj.setClock(CLOCK_FREQUENCY);
+	wireobj.beginTransmission(I2C_EXPANDER_ADDR);
+	wireobj.write(I2C_EXPANDER_CONFIG_REG_ADDR);
+	wireobj.write(I2C_EXPANDER_CONFIG_REG_MASK);
+	wireobj.endTransmission();
+
+	spiobj.begin();
+}
+
+/** 
+ * @brief Function to set the ship select pin of the SPI
+ */
+static void setChipSelect(TwoWire *wireobj, uint8_t mask)
+{
+	// send I2C-Expander device address
+	wireobj->beginTransmission(I2C_EXPANDER_ADDR);
+	// send I2C-Expander output register address
+	wireobj->write(I2C_EXPANDER_OUTPUT_REG_ADDR);
+	// send mask to set output level of GPIO pins
+	wireobj->write(mask);
+	// end communication
+	wireobj->endTransmission();
+}
+
+/**
+ * @brief Function to write the sensor data to the register
+ */
+int8_t commMuxWrite(uint8_t reg_addr, const uint8_t *reg_data, uint32_t length, void *intf_ptr)
+{
+	commMux *comm = (commMux*) intf_ptr;
+	uint32_t i;
+
+	if (comm)
+	{
+		setChipSelect(comm->wireobj, comm->select);
+
+		comm->spiobj->beginTransaction(SPISettings(COMM_SPEED, MSBFIRST, SPI_MODE0));
+		comm->spiobj->transfer(reg_addr);
+		for (i = 0; i < length; i++)
+		{
+			comm->spiobj->transfer(reg_data[i]);
+		}
+		comm->spiobj->endTransaction();
+
+		setChipSelect(comm->wireobj, I2C_EXPANDER_OUTPUT_DESELECT);
+
+		return 0;
+	}
+
+	return 1;
+}
+
+/**
+ * @brief Function to read the sensor data from the register
+ */
+int8_t commMuxRead(uint8_t reg_addr, uint8_t *reg_data, uint32_t length, void *intf_ptr)
+{
+	commMux *comm = (commMux*) intf_ptr;
+	uint32_t i;
+
+	if (comm)
+	{
+		setChipSelect(comm->wireobj, comm->select);
+
+		comm->spiobj->beginTransaction(SPISettings(COMM_SPEED, MSBFIRST, SPI_MODE0));
+		comm->spiobj->transfer(reg_addr);
+		for (i = 0; i < length; i++)
+		{
+			reg_data[i] = comm->spiobj->transfer(0xFF);
+		}
+		comm->spiobj->endTransaction();
+
+		setChipSelect(comm->wireobj, I2C_EXPANDER_OUTPUT_DESELECT);
+
+		return 0;
+	}
+
+	return 1;
+}
+
+void commMuxSwitch(void *intf_ptr)
+{
+	commMux *comm = (commMux*) intf_ptr;
+	
+	if (comm)
+	{
+		setChipSelect(comm->wireobj, comm->select);
+	}
+}
+
+/**
+ * @brief Function to maintain a delay between communication
+ */
+void commMuxDelay(uint32_t period_us, void *intf_ptr)
+{
+	(void) intf_ptr;
+	delayMicroseconds(period_us);
+}