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Daniel Peter Chokola 2 years ago
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  1. 29
      Inc/pcf8523.h
  2. 173
      Src/pcf8523.c
  3. 15
      readme.md

29
Inc/pcf8523.h
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/*
* pcf8523.h
*
* Created on: Mar 25, 2023
* Author: Daniel Peter Chokola
*/
#ifndef PCF8523_INC_PCF8523_H_
#define PCF8523_INC_PCF8523_H_
/* Includes */
#include <stdint.h>
#include "i2c.h"
#include "time.h"
/* Definitions */
/* Data Structures */
typedef struct pcf8523_s {
I2C_HandleTypeDef *hi2c;
} pcf8523_t;
/* Function Prototypes */
int32_t pcf8523_init(pcf8523_t *pcf8523, I2C_HandleTypeDef *hi2c);
time_t pcf8523_now(pcf8523_t *pcf8523);
int32_t pcf8523_set_time_t(pcf8523_t *pcf8523, time_t *time);
int32_t pcf8523_set_time(pcf8523_t *pcf8523, struct tm *t);
#endif /* PCF8523_INC_PCF8523_H_ */

173
Src/pcf8523.c
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/*
* pcf8523.c
*
* Created on: Mar 25, 2023
* Author: Daniel Peter Chokola
*/
/* Includes */
#include "pcf8523.h"
#include "i2c.h"
#include "time.h"
/* Definitions */
/* I2C addresses */
#define PCF_I2C_W (0xd0)
#define PCF_I2C_R (0xd1)
/* Registers */
#define PCF_REG_CONTROL_1 (0x00)
#define PCF_REG_CONTROL_2 (0x01)
#define PCF_REG_CONTROL_3 (0x02)
#define PCF_REG_SECONDS (0x03)
#define PCF_REG_MINUTES (0x04)
#define PCF_REG_HOURS (0x05)
#define PCF_REG_DAYS (0x06)
#define PCF_REG_WEEKDAYS (0x07)
#define PCF_REG_MONTHS (0x08)
#define PCF_REG_YEARS (0x09)
#define PCF_REG_MINUTE_ALARM (0x0A)
#define PCF_REG_HOUR_ALARM (0x0B)
#define PCF_REG_DAY_ALARM (0x0C)
#define PCF_REG_WEEKDAY_ALARM (0x0D)
#define PCF_REG_OFFSET (0x0E)
#define PCF_REG_TMR_CLKOUT_CTRL (0x0F)
#define PCF_REG_TMR_A_FREQ_CTRL (0x10)
#define PCF_REG_TMR_A_REG (0x11)
#define PCF_REG_TMR_B_FREQ_CTRL (0x12)
#define PCF_REG_TMR_B_REG (0x13)
/* Bitmasks */
#define PCF_MASK_CTL1_CAP_SEL (0x80) /* internal oscillator capacitor selection for quartz crystals with a corresponding load capacitance */
#define PCF_MASK_CTL1_STOP (0x20) /* 0 RTC time circuits running; 1 RTC time circuits frozen */
#define PCF_MASK_CTL1_SR (0x10) /* 0 no software reset; 1 initiate software reset */
#define PCF_MASK_CTL1_12_24 (0x08) /* 0 24 hour mode is selected; 1 12 hour mode is selected */
#define PCF_MASK_CTL1_SIE (0x04) /* 0 second interrupt disabled; 1 second interrupt enabled */
#define PCF_MASK_CTL1_AIE (0x02) /* 0 alarm interrupt disabled; 1 alarm interrupt enabled */
#define PCF_MASK_CTL1_CIE (0x01) /* 0 no correction interrupt generated; 1 interrupt pulses are generated at every correction cycle */
#define PCF_MASK_CTL2_WTAF (0x80) /* 0 no watchdog timer A interrupt generated; 1 flag set when watchdog timer A interrupt generated */
#define PCF_MASK_CTL2_CTAF (0x40) /* 0 no countdown timer A interrupt generated; 1 flag set when countdown timer A interrupt generated */
#define PCF_MASK_CTL2_CTBF (0x20) /* 0 no countdown timer B interrupt generated; 1 flag set when countdown timer B interrupt generated */
#define PCF_MASK_CTL2_SF (0x10) /* 0 no second interrupt generated; 1 flag set when second interrupt generated */
#define PCF_MASK_CTL2_AF (0x08) /* 0 no alarm interrupt generated; 1 flag set when alarm triggered */
#define PCF_MASK_CTL2_WTAIE (0x04) /* 0 watchdog timer A interrupt is disabled; 1 watchdog timer A interrupt is enabled */
#define PCF_MASK_CTL2_CTAIE (0x02) /* 0 countdown timer A interrupt is disabled; 1 countdown timer A interrupt is enabled */
#define PCF_MASK_CTL2_CTBIE (0x01) /* 0 countdown timer B interrupt is disabled; 1 countdown timer B interrupt is enabled */
#define PCF_MASK_CTL3_PM (0xe0) /* battery switch-over and battery low detection control */
#define PCF_MASK_CTL3_BSF (0x08) /* 0 no battery switch-over interrupt generated; 1 flag set when battery switch-over occurs */
#define PCF_MASK_CTL3_BLF (0x04) /* 0 battery status ok; 1 battery status low; flag is read-only */
#define PCF_MASK_CTL3_BSIE (0x02) /* 0 no interrupt generated from battery switch-over flag, BSF; 1 interrupt generated when BSF is set */
#define PCF_MASK_CTL3_BLIE (0x01) /* 0 no interrupt generated from battery low flag, BLF; 1 interrupt generated when BLF is set */
#define PCF_CMD_CTL1_RESET (0x58) /* software reset */
/* Slick Macros */
#define bin2bcd(x) ((x / 10) * 6 + x)
#define bcd2bin(x) (x - ((x >> 4) * 6))
#define return_if_fail(cond) \
if(!(cond)) { return; }
#define return_val_if_fail(cond, val) \
if(!(cond)) { return (val); }
#define return_null_if_fail(cond) return_val_if_fail((cond), NULL)
/* Private Variables */
/* Function Prototypes */
static void pcf8253_write_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t data);
static void pcf8253_read_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data);
static void pcf8253_write(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len);
static void pcf8253_read(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len);
/* Function Definitions */
int32_t pcf8523_init(pcf8523_t *pcf8523, I2C_HandleTypeDef *hi2c)
{
uint8_t tmp;
return_val_if_fail(pcf8523, -1);
return_val_if_fail(hi2c, -1);
pcf8523->hi2c = hi2c;
/* initiate reset */
pcf8253_write_byte(pcf8523, PCF_REG_CONTROL_1, PCF_CMD_CTL1_RESET);
/* check if the device is initialized */
pcf8253_read_byte(pcf8523, PCF_REG_CONTROL_3, &tmp);
if((tmp & PCF_MASK_CTL3_PM) == PCF_MASK_CTL3_PM)
{
/* the RTC has not been initialized -- initialize it */
/* FIXME: I don't know how to initialize it. */
/* turn on battery switchover mode */
pcf8253_write_byte(pcf8523, PCF_REG_CONTROL_3, 0x00);
}
return 0;
}
time_t pcf8523_now(pcf8523_t *pcf8523)
{
struct tm t = { 0 };
time_t time;
uint8_t buf[7];
return_val_if_fail(pcf8523, -1);
/* read current time */
pcf8253_read(pcf8523, PCF_REG_SECONDS, buf, 7);
t.tm_sec = bcd2bin(buf[0]);
t.tm_min = bcd2bin(buf[1]);
t.tm_hour = bcd2bin(buf[2]);
t.tm_mday = bcd2bin(buf[3]);
t.tm_wday = bcd2bin(buf[4]); /* ignored by mktime */
t.tm_mon = bcd2bin(buf[5]);
t.tm_year = bcd2bin(buf[6]) + 2000;
time = mktime(&t);
return time;
}
int32_t pcf8523_set_time_t(pcf8523_t *pcf8523, time_t *time)
{
struct tm *t;
return_val_if_fail(pcf8523, -1);
return_val_if_fail(time, -1);
t = gmtime(time);
return pcf8523_set_time(pcf8523, t);
}
int32_t pcf8523_set_time(pcf8523_t *pcf8523, struct tm *t)
{
uint8_t buf[7];
return_val_if_fail(pcf8523, -1);
return_val_if_fail(t, -1);
buf[0] = bin2bcd(t->tm_sec);
buf[1] = bin2bcd(t->tm_min);
buf[2] = bin2bcd(t->tm_hour);
buf[3] = bin2bcd(t->tm_mday);
buf[4] = bin2bcd(t->tm_wday);
buf[5] = bin2bcd(t->tm_mon);
buf[6] = bin2bcd(t->tm_year % 100);
pcf8253_write(pcf8523, PCF_REG_SECONDS, buf, 7);
return 0;
}
static void pcf8253_write_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t data)
{
HAL_I2C_Mem_Write(pcf8523->hi2c, PCF_I2C_W, reg, I2C_MEMADD_SIZE_8BIT, &data, 1, 10);
}
static void pcf8253_read_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data)
{
HAL_I2C_Mem_Read(pcf8523->hi2c, PCF_I2C_R, reg, I2C_MEMADD_SIZE_8BIT, data, 1, 10);
}
static void pcf8253_write(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len)
{
HAL_I2C_Mem_Write(pcf8523->hi2c, PCF_I2C_W, reg, I2C_MEMADD_SIZE_8BIT, data, len, 10);
}
static void pcf8253_read(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len)
{
HAL_I2C_Mem_Read(pcf8523->hi2c, PCF_I2C_R, reg, I2C_MEMADD_SIZE_8BIT, data, len, 10);
}

15
readme.md
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# SX127x
## Introduction
This library implements support for the [PCF8523](https://www.nxp.com/products/peripherals-and-logic/signal-chain/real-time-clocks/rtcs-with-ic-bus/100-na-real-time-clock-calendar-with-battery-backup:PCF8523) real-time clock. It is written for the STM32 HAL using blocking I2C calls.
## Usage
Clone this repository, or add it as a submodule, to your STM32 project under the Drivers/ directory.
Example:
```
#include "pcf8523.h"
pcf8523_t pcf8523;
time_t now;
pcf8523_init(&pcf8523, &hi2c);
now = pcf8523_now(&pcf8523);
```
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