Skovbrynet
I2C
Dependencies: mbed
Fork of
I2C_Debug_for_RealTerm
by 
jim hamblen
Diff: main.cpp
- Revision:
- 1:be1498ba7fb4
- Parent:
- 0:0c54b73b002c
- Child:
- 2:fa8c916b42a9
--- a/main.cpp Tue Mar 08 03:16:34 2011 +0000
+++ b/main.cpp Fri Mar 11 03:25:42 2011 +0000
@@ -1,128 +1,114 @@
#include "mbed.h"
-
// The program sends and receives I2C commands using RealTerm's I2C tab feature
// Run Realterm on PC and this program on mbed
// In RealTerm connect to the mbed's USB virtual COM port
// Switch to I2C tab
// Type in I2C address & data to read and write and see the response
// It is handy to debug complex I2C hardware setups
-// Prints "noack!" when no I2C device responds
+// Prints "No Ack!" when no I2C device responds to the address
+//
+// See Instructions at http://mbed.org/users/4180_1/notebook/i2c-debug-for-realterm/
+//
DigitalOut myled(LED1);
Serial pc(USBTX, USBRX);
I2C i2c(p9,p10);
-char data_length=0;
-int read=0;
-int write=0;
-
-//ugly code structure - should start over and fix this later
-//now that I understand syntax for command strings a bit more - but it works
-// Read in two ASCII characters and convert to a byte
-// ...unless a command character is found
-int getbyte(char *data) {
- char charin=0;
- charin = pc.getc();
- if (charin == 'R') {
- read=1;
- if (getbyte(&data_length)==0) pc.printf("error");
- return 2;
- }
- if (charin == 'P') return 3;
- if (charin > 'F') return 0;
- if (charin <='9') charin = charin - '0';
- else charin = charin +10 - 'A';
- *data = charin << 4;
- charin = pc.getc();
- if (charin > 'F') return 0;
- if (charin <='9') charin = charin - '0';
- else charin = charin +10 - 'A';
- *data = *data | charin;
- return 1;
-}
int main() {
-
- char command=0;
- char address=0x40;
- char data[255];
+ char last_command=0;
+ char current_char=0;
+ char address=0;
+ char data [255];
+ char current_byte=0;
char cmd[255];
int cmd_count=0;
- int more_cmd = 0;
+ int data_count=0;
+ int read=0;
+ int write=0;
+ int first_data_byte=0;
int i=0;
+
myled=1;
- data[0]=0;
- data[1]=0;
i2c.frequency(75000);
i2c.start();
+ i2c.stop();
i2c.start();
- pc.printf("\fmbed I2C ready\n\r");
-// loop forever waiting for PC serial commands
+ i2c.stop();
+// Send a start message to RealTerm
+ pc.printf("\fmbed I2C debug tool ready\n\r");
+// Loop processing command strings from RealTerm
while (1) {
- command = pc.getc();
- switch (command) {
- case 'S':
- //Start - automatic start sent on read or write
- data_length=0;
- cmd_count=0;
- read=0;
- write=0;
- // in case of multiple starts
- while (getbyte(&address)==0) {i2c.start();};
- pc.printf(" - I2C address=%2.2X ", address);
- //odd address means a read, otherwise a write
- if ((address & 0x01) == 1) read=1;
- else write=1;
- if (read ==1) {
- //read number of bytes to read
- if (getbyte(&data_length)==0) break;
+ current_char = pc.getc();
+ // Is it a two character ASCII string data byte value
+ if (current_char <='F') {
+ // convert to a binary byte
+ if (current_char <='9') current_byte = current_char - '0';
+ else current_byte =current_char +10 -'A';
+ current_char = pc.getc();
+ if (current_char >'F') pc.printf("error|\n\r");
+ if (current_char <='9') current_byte = (current_byte <<4) | (current_char - '0');
+ else current_byte = (current_byte <<4)|(current_char +10 -'A');
+ // first byte after S command is the I2C address
+ if (first_data_byte==1) {
+ first_data_byte=0;
+ address=current_byte;
+ pc.printf(" -I2C address=%2.2X ", address);
+ //Odd I2C address is a read and even is a write
+ if ((address & 0x01) == 0) write=1;
+ else read=1;
+ } else
+ // Read in cmd bytes for write
+ if ((last_command == 'S')&&(read==0)) {
+ cmd[cmd_count]=current_byte;
+ cmd_count++;
}
- if (write==1) {
- more_cmd =1;
- while (more_cmd==1) {
- if (getbyte(&cmd[cmd_count])>=2) {
- pc.printf(" write ");
- // write I2C command(s)
- if (i2c.write(address, cmd, cmd_count)!=0) pc.printf(" noack! ");
- for (i=0; i<cmd_count; i++)
- pc.printf(" command=%2.2X ", cmd[i]);
- cmd_count=0;
- more_cmd=0;
- write = 0;
- } else cmd_count++;
+ // number of bytes for a read
+ if ((last_command =='R')||(read==1)) data_count=current_byte;
+ } else {
+ // Not a number - it is a command character
+ last_command = current_char;
+ switch (last_command) {
+ // Start
+ case 'S':
+ first_data_byte=1;
+ break;
+ // Stop
+ case 'P':
+ // Do the I2C write
+ if (write==1) {
+ pc.printf(" write ");
+ if (i2c.write(address,cmd,cmd_count)!=0) pc.printf(" No Ack! ");
+ for (i=0; i<cmd_count; i++)
+ pc.printf(" cmd=%2.2X ", cmd[i]);
}
- if (read==0) pc.printf("\n\r");;
- }
- break;
- case 'P':
- //Stop
- if (read == 1) {
- pc.printf(" read ");
- // read I2C data
- if (i2c.read(address, data, data_length)!=0) pc.printf(" noack! ");
- read = 0;
- write = 0;
- // send I2C data back to PC serial port
- for (i=0; i<data_length; i++)
- pc.printf(" data=%2.2X ",data[i]);
- }
- pc.printf("\n\r");
- data_length=0;
- cmd_count=0;
- i2c.stop();
- break;
- case 'R':
- //automatic read after write - read number of bytes to read
- if (getbyte(&data_length)==0) break;
- break;
- case '?':
- //Status
- pc.printf(" mbed ready \n\r");
- break;
- default:
-
- myled = 0;
- break;
+ // Do the I2C read
+ if (read==1) {
+ pc.printf(" read ");
+ if (i2c.read(address, data, data_count) != 0) pc.printf(" No Ack! ");
+ for (i=0; i<data_count; i++)
+ pc.printf(" data=%2.2X ",data[i]);
+ }
+ // reset values for next I2C operation
+ i2c.stop();
+ pc.printf("\n\r");
+ read=0;
+ data_count=0;
+ cmd_count=0;
+ write=0;
+ first_data_byte=0;
+ break;
+ // Read after write
+ case 'R':
+ read=1;
+ break;
+ // Status request
+ case '?':
+ pc.printf(" mbed ready \n\r");
+ break;
+ // Unknown or unimplemented command
+ default:
+ pc.printf("unknown command");
+ break;
+ }
}
-
-
}
}
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