m41t80.c

// system includes
#include "at91sam7s64.h"
#include "global.h"

// local includes
#include "i2c.h"
#include "rprintf.h"
#include "m41t80.h"

// functions
void m41t80Init(void)
{
    // check if clock is running
    if(m41t80ReadReg(M41T80_REG_SECONDS) & 0x80)
    {
        // STOP bit is set, clock is not running
        // lets start it
        m41t80Reset();
    }
    // otherwise, clock is already running
    // Do not disturb.
}

void m41t80Reset(void)
{
    // reset registers to initialized state
    m41t80WriteReg(M41T80_REG_CTRL, 0x80);
    // start clock
    m41t80WriteReg(M41T80_REG_SECONDS, 0x00);
    // reset time
    m41t80SetTime(0);
    // start clock updates
    m41t80WriteReg(M41T80_REG_AL_HOUR, 0x00);
}

void m41t80WriteReg(u08 regaddr, u08 data)
{
    u08 packet[2];
    // setup write
    packet[0] = regaddr;
    packet[1] = data;
    // write the register
    i2cMasterSend(M41T80_I2C_BASE_ADDR, 2, packet);
}

u08 m41t80ReadReg(u08 regaddr)
{
    u08 data;
    // set register address to read
    i2cMasterSend(M41T80_I2C_BASE_ADDR, 1, &regaddr);
    // read the register
    i2cMasterReceive(M41T80_I2C_BASE_ADDR, 1, &data);
    // return data
    return data;
}

void m41t80SetOutState(int state)
{
    // set the OUT pin state
    // if state == FALSE, OUT is set low
    // if state == TRUE, OUT is set open (open-collector)
    
    // modify OUT bit
    if(state)
        m41t80WriteReg(M41T80_REG_CTRL, m41t80ReadReg(M41T80_REG_CTRL) | 0x80);
    else
        m41t80WriteReg(M41T80_REG_CTRL, m41t80ReadReg(M41T80_REG_CTRL) & ~0x80);
}


void m41t80SetTime(u32 time)
{
    u08 packet[5];

    // prepare write
    packet[0] = M41T80_REG_DSECONDS;
    packet[1] = time>>24;
    packet[2] = time>>16;
    packet[3] = time>>8;
    packet[4] = time;
    // write new time
    i2cMasterSend(M41T80_I2C_BASE_ADDR, 5, packet);
}

u32 m41t80GetTime(void)
{
    u08 reg;
    u32 time;

    // set the register to access
    reg = M41T80_REG_DSECONDS;
    i2cMasterSend(M41T80_I2C_BASE_ADDR, 1, &reg);
    // get the current time
    i2cMasterReceive(M41T80_I2C_BASE_ADDR, 4, (unsigned char*)&time);
    // return time fields
    // -- All fields BCD encoded --
    // bits 31-30 : century bits
    // bits 29-28 : 10's hours
    // bits 27-24 : 1's hours
    // bits 23-20 : 10's minutes
    // bits 19-16 : 1's minutes
    // bits 15-12 : 10's seconds
    // bits 11-08 : 1's seconds
    // bits 07-04 : 0.1's seconds
    // bits 03-00 : 0.01's seconds
    return time;
}

void m41t80PrintTime(u32 time)
{
    // mask off century bits
    time &= 0x3FFFFFFF;
    // print hours
    rprintfu08(time>>24);
    rprintfChar(':');
    // print minutes
    rprintfu08(time>>16);
    rprintfChar(':');
    // print seconds
    rprintfu08(time>>8);
    rprintfChar('.');
    // print decimal seconds
    rprintfu08(time);
}

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