skuodi / Bits_of_Clockwork

HAL I2C library for DS1307 RTC

Bits_of_Clockwork

A HAL-based library for interfacing Maxim Integrated's DS1307 Real-time Clock IC with STM32 via I2C.

Table of Contents

• Features
• Installation
• API Reference
• Usage Examples
• License

Features

• Set second, minute, hour, day date, month and year all in one command.
• Read decoded values of time.
• Set square-wave output settings.

Installation

1. Copy the DS1307.h file into

    [Your Project Folder] > Core > Inc 

2. Copy the DS1307.c file into

    [Your Project Folder] > Core > Src

3. Line 16 of DS1307.h specifies the HAL library for the STM32 board in use. Change it as per your hardware.

   #include "stm32f1xx_hal.h"						//HAL library for the bluepill(STM32F103C8)

4. The next line specifies the handle of the I2C bus in use. Change it as per your schematic.

   extern I2C_HandleTypeDef hi2c2;					//handle for the i2c2 bus connected to my DS1307

API Reference

readTime

Takes an 8-byte array and populates it with decimal values of [second,minute,hour,day,date,month,year, square-wave settings] read from the RTC

void readTime(uint8_t allTime[8])

Parameter	Type	Description
alltime	uint8_t*	Holds the data read.

getSeconds

Takes DS1307 seconds register bits and returns the corresponding decimal value.

uint8_t getSeconds(uint8_t inTime)

Parameter	Type	Description
inTime	uint8_t	Bits from the DS1307 seconds register.

getHours

Takes DS1307 hours register bits and returns the corresponding decimal value.

uint8_t getHours(uint8_t inTime)

Parameter	Type	Description
inTime	uint8_t	Bits from the DS1307 hours register.

getMeridian

Determines whether the RTC is in 12 or 24-hour

char getMeridian()

• Returns H to indicate 24-hour mode and A or P indicating 12-hour mode AM or PM.

getTime

Takes DS1307 minute/day/date/month/year register values and returns a corresponding decimal value.

uint8_t getTime(uint8_t inTime)

Parameter	Type	Description
inTime	uint8_t	Bits from the minute or day or date or month or year register.

setTime

Takes decimal values of [second,minute,hour,day,date,month,year, square-wave settings] and 12/24-hour clock setting and writes them to the RTC

setTime(uint8_t timeSet[8], char meridian)

Parameter	Type	Description
timeSet	uint8_t*	Holds the data to be written to the timekeeper registers.
meridian	char	For the 12 or 24-hour setting.

Usage Examples

Setting the time

	uint8_t pData[] = {0,1,1,4,17,11,21,0b00000011 };	// {sec,min,hour,day date, month,year, squarewave enable 32.768kHz}
	setTime(pData, 'A');								// 01:01:00AM 4 17/11/2021 

• The representation of day of the week is arbitrary but must be sequential...to wit, if 1 corresponds to Monday, 2 will be Tuesday

Reading the time

	uint8_t rData[8]={0};			//holds timekeeper register values
	uint8_t deBug[30]={0};			//holds string to be printed for dedugging
	char meridian;					// 12/24hr more

	readTime(rData);
	meridian = getMeridian();
	sprintf((char *)deBug, " %i:%i:%i%c %i %i/%i/%i\r\n", rData[2], rData[1], rData[0], meridian,rData[3],rData[4],rData[5],rData[6]);
	CDC_Transmit_FS(deBug, 25);

• Here's the output of this code running on a Bluepill configured as a USB Communication Device (Virtual Com Port).

License

MIT