Diff: I2C_hot_read.cpp

Revision:

3:3e8c16b6620c

Child:

4:1c48c9fa44fc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/I2C_hot_read.cpp	Thu Jun 21 22:11:25 2018 +0000
@@ -0,0 +1,156 @@
+#include "mbed.h"
+
+extern Serial pc;
+extern int frequ; //unit kHz
+extern char dev_addr; //fixed
+
+char get_half_byte(int *); //defined in I2C_read.cpp 
+
+void read_bit(int bit_pos) {
+//    pc.printf("\n\r\tstart hot-read");
+    int i;
+    char temp = 0;
+    int delay1 = 20;
+    int delay2 = 2 * delay1;
+    //DigitalIn sda(p9,PullNone);
+    DigitalInOut sda(p9,PIN_OUTPUT,PullNone,1);
+    DigitalOut scl(p10,1);
+    LPC_PINCON->PINMODE_OD0 = (LPC_PINCON->PINMODE_OD0  | 0x0003); // To make p9 & P10 open_drain
+    scl = 1;
+    sda = 1;
+    
+    //Transmit Stop (scl high followed by sda high)
+    sda = 0;
+    wait_us(delay2);
+    scl = 1;
+    wait_us(delay1);
+    sda = 1;
+    
+    //Generater Start
+    wait_us(4);
+    sda = 0;
+    wait_us(delay1);
+    scl = 0;
+    wait_us(delay2);
+    //Txr Dev Addr 0x01 for read
+    for(i = 7; i > 0; i = i-1) {
+        wait_us(delay2);
+        scl = 1;
+        wait_us(delay2);
+        scl = 0;
+    }
+    sda = 1;
+    wait_us(delay2);
+    scl = 1;
+    wait_us(delay2);
+    scl = 0; 
+    wait_us(delay2);    
+    //Recieve ACK
+    sda.input(); 
+    scl = 1;
+    wait_us(delay2);
+    if (sda !=0) {
+        pc.printf("\n\n \r\tNo Ack reg pointer :(");
+        wait_us(20);
+    }
+    scl = 0; 
+    wait_us(10);                  
+    //Start of Hot Read. Move the pointer to corresponding bit
+    for(i = 7; i > bit_pos; i = i-1) {
+        scl = 1;
+        wait_us(delay2);
+        scl = 0;
+        wait_us(delay2);
+    }
+    pc.printf("\n\n\n\r\tWaiting at bit position %d ..... Monitor adc_op_clk pin\n\n\r\tPress 'q' to quit hot read : ", i);    
+    while(temp!='q') {
+        temp = pc.getc();
+    }
+    //send out the remaining clock pulses
+    for(; i >= 0; i = i-1) {
+        scl = 1;
+        wait_us(delay2);
+        scl = 0;
+        wait_us(delay2);
+    }    
+    //Transmit NACK (pull sda high before the 9th pulse)
+    sda.output();
+    sda = 1;
+    wait_us(delay2);
+    scl = 1;
+    wait_us(delay2);
+    scl = 0;
+    wait_us(delay2);
+    sda = 1;
+    wait_us(10);
+    //Transmit Stop (scl high followed by sda high)
+    sda = 0;
+    wait_us(delay2);
+    scl = 1;
+    wait_us(delay1);
+    sda = 1;
+    wait_us(200);  
+    sda.~DigitalInOut();
+    scl.~DigitalOut();   
+} 
+
+void hot_read() {
+    char reg_ptr = 0x55;
+    char temp;
+    int flag1 = 0;
+    char bit_position = 0;
+    I2C i2c(p9,p10);
+    LPC_PINCON->PINMODE_OD0 = (LPC_PINCON->PINMODE_OD0  | 0x0003); // To make p9 & P10 open_drain
+    pc.printf("\n\n\n\r\tYahoooo! Lets Perform a Hot Read");       
+Re_enter:
+    flag1 = 0;
+    //Read Pointer to the Register that needs to be read
+    while (!flag1) {
+        pc.printf("\n\n\r\tEnter Register Address in hex (0 to f): ");
+        reg_ptr = get_half_byte(&flag1);
+        if (flag1==0) pc.printf(" \n\r\t\033[%dm Invalid Chracter!! No worries, let us try again \033[%dm",41,40);
+    }
+    //Read the bit at which hot read is to be performed
+    flag1=0;
+    while (!flag1) {
+        pc.printf("\n\n\r\tEnter bit position to be read (0 to 7): ");
+        bit_position = get_half_byte(&flag1);
+        if (bit_position > 7) flag1 = 0;
+        if (flag1==0) pc.printf(" \n\r\t\033[%dm Invalid Choice!! No worries, let us try again \033[%dm",41,40);
+    }              
+
+    pc.printf("\n\n\n\r\t\033[%dm", 44);//change backround to blue
+    pc.printf(" Device Address (fixed) = 0x%2.2X ; Register Pointer = 0x%2.2X ; bit position = %d ",dev_addr, reg_ptr, bit_position);
+    pc.printf("\033[%dm", 40);//change backround to black
+    
+    pc.printf("\n\n\n\r\tContinue Read? (y/n) [Press 'e' to re-enter]: ");  
+    temp = 0;
+    while ( temp!='y' && temp!='n' && temp!='e') {
+        temp = pc.getc();
+    }
+    if (temp == 'n') {
+        pc.printf("\n\n\r\tAborting Register Read :(");
+        return;
+    }
+    if (temp == 'e') {
+        pc.printf(" \n\n\n\r\tOk, let us try again :)");
+        goto Re_enter;
+    }
+    i2c.frequency(frequ*1000);
+    i2c.stop(); //add a stop after a previous hot-read
+    i2c.start();
+    flag1 = i2c.write(dev_addr); 
+    if (flag1 != 1) pc.printf("\n\n\n\r\tNo Ack for dev addr :(");
+    flag1 = i2c.write(reg_ptr);
+    if (flag1 != 1) pc.printf("\n\n\r\tNo Ack reg pointer :(");
+    i2c.stop(); 
+    pc.printf("\n\n\n\r\tPress 's' to start hot read [Press 'a' to abort] : ");    
+    while(temp!='s' && temp!='a') {
+        temp = pc.getc();
+    } 
+    if (temp == 'a') {
+        pc.printf("\n\n\r\tAborting Register Read :(");
+        return;
+    }
+    read_bit(bit_position);  
+}
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