Initailize repository

1 files changed, 210 insertions, 0 deletions

diff --git a/ds1302.c b/ds1302.c
new file mode 100644
index 0000000..3d1152b
--- /dev/null
+++ b/ds1302.c
@@ -0,0 +1,210 @@
+#include "ds1302.h"
+#include <stdio.h>
+#include <time.h>
+
+uint8_t ds1302_readAddress(uint8_t address) {
+    return address | 0x01;
+}
+
+void ds1302_spi_session_start(struct ds1302_spi_session * session) {
+    /*Setup Pins*/
+    bcm2835_gpio_fsel(session->clock, BCM2835_GPIO_FSEL_OUTP);
+    bcm2835_gpio_fsel(session->select, BCM2835_GPIO_FSEL_OUTP);
+    bcm2835_gpio_fsel(session->io, BCM2835_GPIO_FSEL_OUTP);
+    
+    bcm2835_gpio_write(session->clock, LOW);
+    bcm2835_delayMicroseconds(10);
+    bcm2835_gpio_write(session->select, HIGH);
+    bcm2835_gpio_write(session->io, LOW);
+
+    bcm2835_delayMicroseconds(10);
+}
+
+void ds1302_spi_session_end(struct ds1302_spi_session  * session) {
+    bcm2835_gpio_write(session->select, LOW);
+    bcm2835_delayMicroseconds(10);
+}
+
+void ds1302_spi_session_write(struct ds1302_spi_session * session, int8_t value) {
+    bcm2835_gpio_fsel(session->io, BCM2835_GPIO_FSEL_OUTP);
+
+    for(int i = 0; i < 8; i++) {
+        /*The LSB is written first*/
+        uint8_t out = value & 0x01;
+        value = value >> 1;
+
+        uint8_t o;
+        if(out != 0x0)
+            o = HIGH;
+        else
+            o = LOW;
+        
+        /*ds1302 reads the value while the clock is high. Ensure that value is written*/
+        bcm2835_gpio_write(session->io, o);
+        bcm2835_delayMicroseconds(DS1302_CLOCKDELAY);
+        bcm2835_gpio_write(session->clock, HIGH);
+        /*TODO: Lookup the required wait time*/
+        bcm2835_delayMicroseconds(DS1302_CLOCKDELAY);
+        bcm2835_gpio_write(session->clock, LOW);
+    }
+}
+
+uint8_t ds1302_spi_session_read(struct ds1302_spi_session * session) {
+    bcm2835_gpio_fsel(session->io, BCM2835_GPIO_FSEL_INPT);
+    uint8_t value = 0;
+
+    /*The LSB is read first*/
+    for(int i = 0; i < 8; i++) {
+        value = value >> 1 | bcm2835_gpio_lev(session->io) << 7;
+
+        bcm2835_gpio_write(session->clock, HIGH);
+        bcm2835_delayMicroseconds(DS1302_CLOCKDELAY);
+        bcm2835_gpio_write(session->clock, LOW);
+        //bcm2835_delayMicroseconds(DS1302_CLOCKDELAY);
+    }
+
+    return value;
+}
+
+uint8_t ds1302_set_writeprotect(struct ds1302_spi_session * session, uint8_t protect) {
+    if(protect != 0x0)
+        protect = 0x80;
+
+    ds1302_spi_session_write(session, DS1302_WRITE_PROTECT);
+    ds1302_spi_session_write(session, protect);
+}
+
+uint8_t ds1302_read_register(struct ds1302_spi_session * session, uint8_t address) {
+    ds1302_spi_session_write(session, ds1302_readAddress(address));
+    return ds1302_spi_session_read(session);
+}
+
+void ds1302_write_register(struct ds1302_spi_session * session, uint8_t address, uint8_t data) {
+    ds1302_spi_session_write(session, address);
+    ds1302_spi_session_write(session, data);
+}
+
+uint8_t ds1302_burst_read(struct ds1302_spi_session * session, ds1302BurstType type, uint8_t * output, size_t size) {
+    if(size <= 0)
+        return 0;
+
+    uint8_t command = ds1302_readAddress(DS1302_CLOCK_BURST);
+    uint8_t bytesRead = 0;
+    
+    if(type == DS1302_MEMORY)
+        command = command | 0x40;
+
+    ds1302_spi_session_write(session, command);
+    /*read more about burst reads from memory*/
+    for(int i = 0; i < size && i < 9; i++) {
+        output[i] = ds1302_spi_session_read(session);
+        bytesRead++;
+    }
+
+    /*Pull the select line down to signal that we are done reading*/
+    bcm2835_gpio_write(session->select, LOW);
+    bcm2835_delayMicroseconds(10);
+    bcm2835_gpio_write(session->select, HIGH);
+
+    return bytesRead;
+}
+uint8_t ds1302_burst_write(struct ds1302_spi_session * session, ds1302BurstType type, uint8_t * input, size_t size) {
+    if(size <= 0)
+        return 0;
+
+    uint8_t command = DS1302_CLOCK_BURST;
+    uint8_t bytesWritten = 0;
+    
+    if(type == DS1302_MEMORY)
+        command = command | 0x40;
+
+    ds1302_spi_session_write(session, command);
+
+    for(int i = 0; i < size; i++) {
+        ds1302_spi_session_write(session, input[i]);
+        bytesWritten++;
+    }
+
+    /*Pull the select line down to signal that we are done writing*/
+    bcm2835_gpio_write(session->select, LOW);
+    bcm2835_delayMicroseconds(10);
+    bcm2835_gpio_write(session->select, HIGH);
+
+    return bytesWritten;
+}
+
+/*Convert the base 10 hex representation to just base 10
+  The upper half represents the tens digit and the lower half 
+  represents the ones digit.
+  Make sure to clear any bits that are not used in the representation.
+  (EG the 12/24 and AM/PM bits for the hour register)
+*/
+uint8_t ds1302_convertToDecimal(uint8_t input) {
+    uint8_t result = 0x0;
+    result = ((input >> 4) * 10) + (input & 0x0F);
+    return result;
+}
+
+/*Convert base 10 to the 10 hex representation
+    Inverse of ds1302_convertToDecimal
+*/
+uint8_t ds1302_convertToDecimalHex(uint8_t input) {
+    uint8_t result = 0x0;
+    uint8_t tens = input / 10;
+    uint8_t ones = input - (tens * 10);
+    result = (tens << 4) | ones;
+    return result;
+}
+
+void ds1302_getCalendarTime(struct ds1302_spi_session * session, struct tm * date) {
+    uint8_t data[7] = {0xff};
+    /*Clock hour format: High: 12hr, Low: 24h*/
+    uint8_t h12;
+    /*PM or AM: High: PM, Low: AM*/
+    uint8_t pm;
+    uint8_t hour;
+
+    ds1302_burst_read(session, DS1302_REGISTER, data, 7);
+
+    date->tm_sec = ds1302_convertToDecimal(data[0] & (~0x80));
+    date->tm_min = ds1302_convertToDecimal(data[1] & (~0x80));
+
+    /*struct tm represents hours in 24 format. Convert the 12hr clock to 24hr*/
+    h12 = data[2] & 0x80;
+    pm = data[2] & 0x20;
+    hour = ds1302_convertToDecimal(data[2] & 0x1F);
+    if(h12) {
+        if(pm) {
+            date->tm_hour = hour + 11;
+        } else {
+            date->tm_hour = hour - 1;
+        }
+    } else {
+        date->tm_hour = hour;
+    }
+
+    date->tm_mday = ds1302_convertToDecimal(data[3]);
+    /*struct tm starts counting from 0 whereas the ds1302 starts from 1*/
+    date->tm_mon = ds1302_convertToDecimal(data[4]) - 1;
+    /*struct tm starts counting from 0 whereas the ds1302 starts from 1*/
+    date->tm_wday = ds1302_convertToDecimal(data[5]) - 1;    
+    /*Number of year that have passed since 1900*/
+    date->tm_year = (ds1302_convertToDecimal(data[6]) + DS1302_START_YEAR) - 1900;
+}
+
+void ds1302_setCalendarTime(struct ds1302_spi_session * session, struct tm * date) {
+    /*TODO: disable Write protect*/
+    uint8_t data[8] = {0};
+    uint8_t hour = 0;
+    
+    data[0] = ds1302_convertToDecimalHex(date->tm_sec);
+    data[1] = ds1302_convertToDecimalHex(date->tm_min);
+    data[2] = ds1302_convertToDecimalHex(date->tm_hour);
+    data[3] = ds1302_convertToDecimalHex(date->tm_mday);
+    data[4] = ds1302_convertToDecimalHex(date->tm_mon + 1);
+    data[5] = ds1302_convertToDecimalHex(date->tm_wday + 1);
+    data[6] = ds1302_convertToDecimalHex((date->tm_year + 1900) - DS1302_START_YEAR);
+    data[7] = 0x00;
+
+    ds1302_burst_write(session, DS1302_REGISTER, data, 8);
+}