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kmp84
Joined: 02 Feb 2010
Posts: 345
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| MCP79410 driver |
 Posted: Sat Apr 06, 2019 3:25 pm |
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Hello All,
Is there some working driver for MCP79410 RTC chip? I tried with some my modification, but it did not succeed.
Best Regards! |
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temtronic
Joined: 01 Jul 2010
Posts: 9174
Location: Greensville,Ontario
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| Posted: Sat Apr 06, 2019 7:30 pm |
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With every I2C device, use PCM P's I2C scanner program from the code library to confirm the PIC can communicate with the I2C device.
I did a quick read of the datasheet and the base address appears to be 0xDE.
Have you the correct I2C bus pullups?
Have you a coin cell battery connected ?
Is this just the chip or a premade 'module'? If a module, post a link to it's datasheet.
What PIC ??
Show us your code ! It might be a simple mistype.
Jay |
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kmp84
Joined: 02 Feb 2010
Posts: 345
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| Posted: Sun Apr 07, 2019 4:02 am |
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Hi mr."temtronic",
I forgot to say that:
1. PCM's scanner program found slave address 0xAE, 0xDE;
2. Have been connected pull-up 4k7;
3. Have been connected backup source to pin 'vbat'.
Here is sample test program:
| Code: |
#include <33EP512MU810.h>
#device ICSP=1
#use delay(crystal=8MHz, clock=8MHz)
#FUSES NOWDT //No Watch Dog Timer
#FUSES CKSFSM //Clock Switching is enabled, fail Safe clock monitor is enabled
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOJTAG //JTAG disabled
#FUSES NOPROTECT
/* HW UART4 */
#pin_select U4RX=PIN_E6 // Rx Com4.
#pin_select U4TX=PIN_E7 // Tx Com4.
#define RS485_EN_UART4 PIN_D4 // RE/DE Com4.
#use rs232(UART4,baud=9600,errors,enable=RS485_EN_UART4)
//#define RTC_SDA2 PIN_F4
//#define RTC_SCL2 PIN_F5
#use i2c(master, I2C2)
//#define MCP7941x_EEPROM_I2C_ADDR 0xAE
#define MCP7941x_RTC_I2C_ADDR 0xDE
#define RTC_LOCATION 0x00
BYTE bin2bcd(BYTE binary_value){
BYTE temp;
BYTE retval;
temp = binary_value;
retval = 0;
while(1)
{
// Get the tens digit by doing multiple subtraction
// of 10 from the binary value.
if(temp >= 10)
{
temp -= 10;
retval += 0x10;
}
else // Get the ones digit by adding the remainder.
{
retval += temp;
break;
}
}
return(retval);
}
// Input range - 00 to 99.
BYTE bcd2bin(BYTE bcd_value){
BYTE temp;
temp = bcd_value;
// Shifting upper digit right by 1 is same as multiplying by 8.
temp >>= 1;
// Isolate the bits for the upper digit.
temp &= 0x78;
// Now return: (Tens * 8) + (Tens * 2) + Ones
return(temp + (temp >> 2) + (bcd_value & 0x0f));
}
// Get the date/time:
void MCP7941x_getDateTime(
byte &second,
byte &minute,
byte &hour,
byte &dayOfWeek,
byte &dayOfMonth,
byte &month,
byte &year)
{
i2c_start();
i2c_write(MCP7941x_RTC_I2C_ADDR);
i2c_write(RTC_LOCATION);
i2c_start();
i2c_write(MCP7941x_RTC_I2C_ADDR+1);
// A few of these need masks because certain bits are control bits
second = bcd2bin(i2c_read() & 0x7f); // 01111111
minute = bcd2bin(i2c_read() & 0x7f); // 01111111
hour = bcd2bin(i2c_read() & 0x3f); // 00111111
dayOfWeek = bcd2bin(i2c_read() & 0x07); // 01111111
dayOfMonth = bcd2bin(i2c_read() & 0x3f); // 00111111
month = bcd2bin(i2c_read() & 0x1f); // 00011111
year = bcd2bin(i2c_read()); // 11111111
i2c_stop();
}
// Set the date/time, set to 24hr and enable the clock:
// (assumes you're passing in valid numbers)
void MCP7941x_setDateTime(
byte second, // 0-59
byte minute, // 0-59
byte hour, // 1-23
byte dayOfWeek, // 1-7
byte dayOfMonth, // 1-28/29/30/31
byte month, // 1-12
byte year) // 0-99
{
i2c_start();
i2c_write(MCP7941x_RTC_I2C_ADDR);
i2c_write(RTC_LOCATION);
i2c_write(bin2bcd(second) & 0x7f); // set seconds and disable clock (01111111)
i2c_write(bin2bcd(minute) & 0x7f); // set minutes (01111111)
i2c_write(bin2bcd(hour) & 0x3f); // set hours and to 24hr clock (00111111)
i2c_write(0x08 | (bin2bcd(dayOfWeek) & 0x07)); // set the day and enable battery backup (00000111)|(00001000)
i2c_write(bin2bcd(dayOfMonth) & 0x3f); // set the date in month (00111111)
i2c_write(bin2bcd(month) & 0x1f); // set the month (00011111)
i2c_write(bin2bcd(year)); // set the year (11111111)
i2c_stop();
// Start Clock:
i2c_start();
i2c_write(MCP7941x_RTC_I2C_ADDR);
i2c_write(RTC_LOCATION);
i2c_write(bin2bcd(second) | 0x80); // set seconds and enable clock (10000000)
i2c_stop();
}
void main(){
delay_ms(1000);
BYTE second;
BYTE minute;
BYTE hour;
BYTE dayOfWeek;
BYTE dayOfMonth;
BYTE month;
BYTE year;
printf("\n\rMCP7941x_RTC_EXMPLE....");
/*
// Set the date/time, set to 24hr and enable the clock:
// (assumes you're passing in valid numbers)
void MCP7941x_setDateTime(
byte second, // 0-59
byte minute, // 0-59
byte hour, // 1-23
byte dayOfWeek, // 1-7
byte dayOfMonth, // 1-28/29/30/31
byte month, // 1-12
byte year) // 0-99
*/
MCP7941x_setDateTime(0, 1, 13, 7, 7, 4, 19);
for(;;){
MCP7941x_getDateTime(second, minute, hour, dayOfWeek, dayOfMonth, month, year);
printf("\r\nDATA: %02d/\%02d/\%02d",dayOfMonth,month,year);
printf(" TIME:\%02d:\%02d:\%02d\r\n",hour,minute,second);
delay_ms(1000);
}
}
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and print result:
MCP7941x_RTC_EXMPLE....
DATA: 45/25/-91 TIME:45:85:85
DATA: 45/25/-91 TIME:45:85:85
DATA: 45/25/-91 TIME:45:85:85
DATA: 45/25/-91 TIME:45:85:85 |
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temtronic
Joined: 01 Jul 2010
Posts: 9174
Location: Greensville,Ontario
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| Posted: Sun Apr 07, 2019 5:54 am |
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I've seen the '45' and '85' magical numbers before, and are indicating you're not either setting the RTC or starting the RTC or maybe a bad 32KHz xtal.
4K7 pullups are OK for 5 volts, 3k3 for 3 volts.
You should probably set the I2C speed for SLOW although it's rated to 400KHz, you need to be sure pullups are designed for that as well as board layout.
I don't have one to test here so I can't confirm/deny your code is good.
Jay |
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