178 lines
3.7 KiB
C
178 lines
3.7 KiB
C
// This program acts as the device (slave) for the control program i2c/a2a/c_ctl
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#define F_CPU 8000000L
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#include <stdio.h>
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#include <avr/io.h>
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#include <util/delay.h>
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#include <avr/interrupt.h>
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#include "usiTwiSlave.h"
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#define I2C_SLAVE_ADDRESS 0x8 // the 7-bit address (remember to change this when adapting this example)
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enum
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{
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kCS13_10_idx = 0, // Timer 1 Prescalar (CS13,CS12,CS11,CS10) from Table 12-5 pg 89
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kOCR1C_idx = 1, // OCR1C timer match value
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};
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volatile uint8_t ctl_regs[] =
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{
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0x0f, // clk/16384
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244, // OCR1C
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};
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// Tracks the current register pointer position
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volatile uint8_t reg_position = 0;
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const uint8_t reg_size = sizeof(ctl_regs);
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ISR(TIMER1_OVF_vect)
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{
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PINB = _BV(PINB4); // writes to PINB toggle the pins
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}
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void timer_init()
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{
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TIMSK &= ~_BV(TOIE1); // Disable interrupt TIMER1_OVF
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OCR1A = 255; // Set to anything greater than OCR1C (the counter never gets here.)
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TCCR1 |= _BV(CTC1); // Reset TCNT1 to 0 when TCNT1==OCR1C
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TCCR1 |= _BV(PWM1A); // Enable PWM A
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TCCR1 |= ctl_regs[kCS13_10_idx] & 0x0f;
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OCR1C = ctl_regs[kOCR1C_idx];
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TIMSK |= _BV(TOIE1); // Enable interrupt TIMER1_OVF
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}
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/**
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* This is called for each read request we receive, never put more
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* than one byte of data (with TinyWireS.send) to the send-buffer when
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* using this callback
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*/
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void on_request()
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{
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// read and transmit the requestd position
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usiTwiTransmitByte(ctl_regs[reg_position]);
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// Increment the reg position on each read, and loop back to zero
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reg_position++;
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if (reg_position >= reg_size)
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{
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reg_position = 0;
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}
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}
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/**
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* The I2C data received -handler
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*
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* This needs to complete before the next incoming transaction (start,
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* data, restart/stop) on the bus does so be quick, set flags for long
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* running tasks to be called from the mainloop instead of running
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* them directly,
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*/
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void on_receive( uint8_t howMany )
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{
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if (howMany < 1)
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{
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// Sanity-check
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return;
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}
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if (howMany > TWI_RX_BUFFER_SIZE)
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{
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// Also insane number
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return;
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}
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// get the register index to read/write
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reg_position = usiTwiReceiveByte();
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howMany--;
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// If only one byte was received then this was a read request
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// and the buffer pointer (reg_position) is now set to return the byte
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// at this location on the subsequent call to on_request() ...
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if (!howMany)
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{
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return;
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}
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// ... otherwise this was a write request and the buffer
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// pointer is now pointing to the first byte to write to
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while(howMany--)
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{
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ctl_regs[reg_position] = usiTwiReceiveByte();
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if(reg_position == kCS13_10_idx || reg_position == kOCR1C_idx )
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timer_init();
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reg_position++;
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if (reg_position >= reg_size)
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{
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reg_position = 0;
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}
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}
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}
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int main(void)
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{
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cli(); // mask all interupts
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DDRB |= _BV(DDB4); // setup PB4 as output
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PORTB &= ~_BV(PINB4);
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timer_init();
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// setup i2c library
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usi_onReceiverPtr = on_receive; //on_receive;
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usi_onRequestPtr = on_request;
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usiTwiSlaveInit(I2C_SLAVE_ADDRESS);
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sei();
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PINB = _BV(PINB4); // writes to PINB toggle the pins
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_delay_ms(1000);
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PINB = _BV(PINB4); // writes to PINB toggle the pins
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while(1)
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{
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//_delay_ms(1000);
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if (!usi_onReceiverPtr)
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{
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// no onReceive callback, nothing to do...
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continue;
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}
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if (!(USISR & ( 1 << USIPF )))
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{
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// Stop not detected
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continue;
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}
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uint8_t amount = usiTwiAmountDataInReceiveBuffer();
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if (amount == 0)
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{
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// no data in buffer
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continue;
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}
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usi_onReceiverPtr(amount);
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}
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return 0;
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}
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