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RHA
Joined: 25 Apr 2006
Posts: 31
Location: Germany
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| Simple RS232 <--> I2C with very small protocol |
 Posted: Tue Apr 25, 2006 5:07 am |
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A simple RS232 <--> I2C Communication with very small protocol :
Sending 0x00 from PC to Hardware for Connect-Inquiry gets 0x00 as an answer from the hardware.
Then the first byte high-nibble are the number of bytes to send to I2C and the low-nibble are the numer of bytes to receive from I2C (leave 0 if not needed).
The next bytes are the bytes which would be sended to I2C.
If all Data is collected the hardware sends a 0xe0 to the PC for confirmation.
At next the hardware sends/receives data to/from I2C and puts the received data to the RS232.
After all the hardware sends a 0xee to the PC.
Itīs a simple way to test some I2C-Hardware.
Greets
RHA
| Code: |
#include <16F876.h>
#define CLOCK_SPEED 8000000 // Hz
#use delay(clock=CLOCK_SPEED, RESTART_WDT)
#fuses HS,WDT,NOPROTECT,PUT,NOBROWNOUT,NOLVP,NOCPD,NOWRT
#zero_ram
#byte TMR0 = 0x01
#byte PCL = 0x02
#byte STATUS = 0x03
#byte FSR = 0x04
#byte PortA = 0x05
#byte PortB = 0x06
#byte PortC = 0x07
#bit STAT_C = STATUS.0
//***************************************************************************************************************************
//***************************************************************************************************************************
//#bit = PortA.0 //
//#bit = PortA.1 //
//#bit = PortA.2 //
//#bit = PortA.3 //
//#bit = PortA.4 //
//#bit = PortA.5 //
#define TrisA_Ini 0b11111111 // PortA Input/Output
#define PortA_Ini 0b00000000 // PortA Output Init
//-----------------------------------------------------------------------------------
//#bit = PortB.0 //
//#bit = PortB.1 //
//#bit = PortB.2 //
//#bit = PortB.3 //
//#bit = PortB.4 //
//#bit = PortB.5 //
//#bit PGC = PortB.6 //
//#bit PGD = PortB.7 //
#define TrisB_Ini 0b11111111 // PortB Input/Output
#define PortB_Ini 0b00000000 // PortC Output Init
//-----------------------------------------------------------------------------------
//#bit = PortC.0 //
//#bit = PortC.1 //
//#bit = PortC.2 //
//#bit SCL = PortB.3 //
//#bit SDA = PortB.4 //
//#bit = PortB.5 //
//#bit TX = PortC.6 //
//#bit RX = PortC.7 //
#define TrisC_Ini 0b11111111 // PortC Input/Output
#define PortC_Ini 0b00000000 // PortC Output Init
//-----------------------------------------------------------------------------------
// Variables for generate basic timers //
int Pre_01ms; // Prescaler 1ms
int Pre_50ms; // Prescaler 50ms
int Pre_01s; // Prescaler 1s
short CLK_01ms; // 1ms ready
#define Time_RTCC 0xc8 // RTCC 200us (0.0002 / (((1 / 8MHz) * 4) * 2))
#define Time_01ms 0x05 // Prescaler 1ms ( 5*Time_RTCC)
#define Time_50ms 0x32 // Prescaler 50ms ( 50*Time_01ms)
#define Time_01s 0x14 // Prescaler 1s ( 20*Time_50ms)
//-----------------------------------------------------------------------------------
// Variables for the RS232-Connection //
int RS232_Rx; // Inputbyte
int RS232_Tx[15]; // Outputbytes
int RS232_TxCount; // Counter for Outputbytes
//-----------------------------------------------------------------------------------
// Variablen für die RS232-Schnittstelle //
int I2C_Rx; // Inputbyte
int I2C_RxCount; // Counter for Inputbytes
int I2C_Tx[5]; // Outputbytes
int I2C_TxCount; // Counter for Outputbytes
int I2C_TxPtr; // Pointer for Outputbytes
//-----------------------------------------------------------------------------------
#use rs232 (baud=9600,xmit=PIN_C6,rcv=PIN_C7, RESTART_WDT)
#use i2c (master,slow,sda=PIN_C4,scl=PIN_C3,force_HW,RESTART_WDT)
//***************************************************************************************************************************
//***************************************************************************************************************************
#int_rtcc // Serviceroutine for RTCC
rtcc_isr() {
TMR0 = TMR0 - Time_RTCC; // Restart Counter (Overflow would be considered)
if (!--Pre_01ms) { // 1ms ready ?
CLK_01ms = True; // Yes --> Set Indicator
Pre_01ms = Time_01ms; // Reset Prescaler
}
}
//***************************************************************************************************************************
//***************************************************************************************************************************
void send_RS232(int Tx_Byte) { // Send a Byte over RS232
if (RS232_TxCount < 15) { // Another free byte in buffer ?
RS232_Tx[RS232_TxCount] = Tx_Byte; // Write byte in buffer
++RS232_TxCount; // Increment Buffer-Counter
enable_interrupts(INT_TBE); // Enable RS232-Transmit
}
}
//***************************************************************************************************************************
//***************************************************************************************************************************
void I2C_TxRx() { // Send/Receive at I2C
if (I2C_TxCount && (I2C_TxCount == I2C_TxPtr)) { // Data for sending collected?
send_RS232(0xe0); // Send confirmation on RS232
I2C_TxPtr = 0; // Reset pointer from I2C-Sendingbuffer
i2c_start(); // Start I2C-Communication
while (I2C_TxCount) { // Send data on I2C-Bus
i2c_write(I2C_Tx[I2C_TxPtr]); //
--I2C_TxCount; //
++I2C_TxPtr; //
}
while (I2C_RxCount) { // Receive data from I2C-Bus
I2C_Rx = i2c_read(); //
send_RS232(I2C_Rx); //
--I2C_RxCount; //
}
i2c_stop(); // Stop I2C-Communication
I2C_TxPtr = 0; // Reset pointer from I2C-Receivebuffer
send_RS232(0xee); // Send End-Code on RS232
}
}
//***************************************************************************************************************************
//***************************************************************************************************************************
#int_rda // Serviceroutine for RS232 Receive
rda_isr() {
RS232_Rx = getc(); // Read-Out received byte
if (!I2C_TxCount) { // Starting protocol (first byte) ?
if (RS232_Rx == 0x00) { // Connect-Inquiry ?
send_RS232(0x00); // Yes --> Answer
}
else { // No --> Load counter for protocol
I2C_RxCount = RS232_Rx & 0x0f ; // (Receive-Counter)
I2C_TxCount = swap(RS232_Rx) & 0x0f; // (Send-Counter)
}
}
else { // Collect I2C-Sendingdata ?
I2C_Tx[I2C_TxPtr] = RS232_Rx; // Put received byte in I2C-Sendingbuffer
++I2C_TxPtr; // Increment pointer on I2C-Sendingbuffer
}
}
//***************************************************************************************************************************
//***************************************************************************************************************************
#int_tbe // Serviceroutine for RS232 Transmit
tbe_isr() {
if (RS232_TxCount != 0) { // Another Byte ?
putc(RS232_Tx[0]); // Send first byte in buffer
--RS232_TxCount; // Decrement counter
memcpy(RS232_Tx,RS232_Tx+1,14); // Shift buffer
}
else { // Last byte transmitted ?
disable_interrupts(INT_TBE); // Disable RS232-Transmit
}
}
//***************************************************************************************************************************
//***************************************************************************************************************************
void timer() { // Softwaretimer
if (CLK_01ms) { // 1ms ready ?
CLK_01ms = False; // Reset statusbit
if (!--Pre_50ms) { // Decrement Counter for 50ms
Pre_50ms = Time_50ms; // Reset Counter
if (!--Pre_01s) { // Decrement Counter for 1s
Pre_01s = Time_01s; // Reset Counter
}
}
}
}
//***************************************************************************************************************************
//***************************************************************************************************************************
void init() { // Initialisation
PortA = PortA_Ini; // Preset Outputs
PortB = PortB_Ini; //
PortC = PortC_Ini; //
set_tris_a (TrisA_Ini); // Set Inputs/Outputs
set_tris_b (TrisB_Ini); //
set_tris_c (TrisC_Ini); //
port_b_pullups(TRUE); // Switch on PortB - Pullups
setup_adc_ports(NO_ANALOGS); // No Analoginputs
setup_adc(ADC_CLOCK_DIV_2); //
Pre_01ms = Time_01ms; // Preset Prescaler
Pre_50ms = Time_50ms; //
Pre_01s = Time_01s; //
// setup_ccp1(CCP_PWM); // Setup PWM
// set_pwm1_duty(MOT_DISABLE); //
// out_PWM = MOT_DISABLE; //
// setup_timer_3(T3_DISABLED); // Timer3 (not needed)
setup_timer_2(T2_DISABLED,0,1); // Timer2 (not needed)
setup_timer_1(T1_DISABLED); // Timer1 (not needed)
setup_counters(RTCC_INTERNAL,RTCC_DIV_2); // Timer0 for RTCC
set_rtcc(-Time_RTCC); // Set RTCC-Initialvalue
enable_interrupts(INT_RTCC); // Enable RTCC-Interrupt
enable_interrupts(INT_RDA); // Enable RS232-Receive
enable_interrupts(GLOBAL); // Enable Interrupts global
}
//***************************************************************************************************************************
//***************************************************************************************************************************
void main() { // Main loop
init(); // Initialise Program
while(true) {
restart_WDT(); // Reset Watchdog
timer(); // Softwaretimer
I2C_TxRx(); // Send/Receive on I2C
}
}
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kender
Joined: 09 Aug 2004
Posts: 768
Location: Silicon Valley
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RHA
Joined: 25 Apr 2006
Posts: 31
Location: Germany
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| Posted: Tue Apr 25, 2006 2:43 pm |
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Pretty cool,
but i think for most persons itīs easier to work with a standard terminal program and a RS232 connection then with the parallel port.
ciao
RHA |
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