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113 lines
3.3 KiB
C
113 lines
3.3 KiB
C
/*
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* Copyright (C) 2018 Eistec AB
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*
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*/
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/**
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* @ingroup drivers_ds3234
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* @{
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*
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* @file
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* @brief Driver for the DS3234 Extremely Accurate SPI Bus RTC with
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* Integrated Crystal and SRAM, from Maxim
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*
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* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
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* @}
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*/
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#include <stdint.h>
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#include <errno.h>
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#include "ds3234.h"
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#include "ds3234_regs.h"
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#define ENABLE_DEBUG 0
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#include "debug.h"
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/* SPI command byte parameters */
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#define DS3234_CMD_READ (0x00)
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#define DS3234_CMD_WRITE (0x80)
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/**
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* @brief Read one or more registers from the sensor
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*
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* @param[in] dev device descriptor
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* @param[in] addr register address
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* @param[in] len number of bytes to read
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* @param[out] buf destination buffer
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*/
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static void ds3234_read_reg(const ds3234_params_t *dev, uint8_t addr, size_t len, uint8_t *buf)
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{
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uint8_t command = DS3234_CMD_READ | addr;
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/* Acquire exclusive access to the bus. */
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spi_acquire(dev->spi, dev->cs, SPI_MODE_3, dev->clk);
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/* Perform the transaction */
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spi_transfer_regs(dev->spi, dev->cs, command, NULL, buf, len);
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/* Release the bus for other threads. */
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spi_release(dev->spi);
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}
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/**
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* @brief Write a register value to the sensor
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*
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* @param[in] dev device descriptor
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* @param[in] addr register address
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* @param[in] len register size
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* @param[in] buf source buffer
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*/
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static void ds3234_write_reg(const ds3234_params_t *dev, uint8_t addr, size_t len, const uint8_t *buf)
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{
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uint8_t command = DS3234_CMD_WRITE | addr;
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/* Acquire exclusive access to the bus. */
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spi_acquire(dev->spi, dev->cs, SPI_MODE_3, dev->clk);
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/* Perform the transaction */
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spi_transfer_regs(dev->spi, dev->cs, command, buf, NULL, len);
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/* Release the bus for other threads. */
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spi_release(dev->spi);
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}
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int ds3234_pps_init(const ds3234_params_t *dev)
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{
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/* initialize CS pin */
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int res = spi_init_cs(dev->spi, dev->cs);
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if (res < 0) {
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return DS3234_NO_SPI;
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}
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DEBUG("ds3234: init on SPI_DEV(%u)\n", dev->spi);
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if (IS_ACTIVE(ENABLE_DEBUG)) {
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for (int k = 0; k <= 0x19; ++k) {
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uint8_t dbg_reg = 0;
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ds3234_read_reg(dev, k, 1, &dbg_reg);
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DEBUG("%2x: %2x\n", k, dbg_reg);
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}
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}
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uint8_t reg = 0;
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ds3234_read_reg(dev, DS323X_REG_CONTROL, 1, ®);
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/* set reg to a non-zero known value to check if device is present */
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reg |= DS323X_REG_CONTROL_RS1_MASK;
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ds3234_write_reg(dev, DS323X_REG_CONTROL, 1, ®);
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uint8_t readback = 0;
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ds3234_read_reg(dev, DS323X_REG_CONTROL, 1, &readback);
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if (reg != readback) {
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DEBUG("ds3234: readback mismatch: expected %u, actual %u\n", (unsigned)reg, (unsigned)readback);
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return DS3234_NO_DEV;
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}
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/* The control register is configured to:
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* - Enable the oscillator
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* - Enable an square wave output on the SQW pin
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* - Sets the square wave frequency to 1 Hz
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*/
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reg &= ~(DS323X_REG_CONTROL_EOSC_MASK | DS323X_REG_CONTROL_INTCN_MASK |
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DS323X_REG_CONTROL_RS1_MASK | DS323X_REG_CONTROL_RS2_MASK);
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ds3234_write_reg(dev, DS323X_REG_CONTROL, 1, ®);
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return DS3234_OK;
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}
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