118 lines
2.3 KiB
C
118 lines
2.3 KiB
C
#include "common.h"
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#include "bus/usart.h"
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#include "bus/twi.h"
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#include <avr/interrupt.h>
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#include <assert.h>
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// ADS1115 (ADC)
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// PCA9546 (Multiplexer TWI)
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// ATH20 (3x)
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// BMP280 (3x)
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// PB0 Mosfet 1 Peltier
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// PB1 Mosfet 2 Heating
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// PB2 Mosfet 3 Lights
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// PD4 PWM Peltier Hot Side
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// PD5 PWM Peltier Cold Side
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// PD7 PWM Heating
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// PC0 TWI Multiplexer SCL
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// PC1 TWI Multiplexer SDA
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// PD0 Serial USART RX
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// PD1 Serial USART TX
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static void SetPinDefaults(void);
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static void SetTWIChannel(int channel);
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int main(void)
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{
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SetPinDefaults();
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USART_Init();
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TWI_Init();
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sei();
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Info("Initializing...");
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SetTWIChannel(0);
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Sleep(500);
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return 0;
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}
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static void SetPinDefaults(void)
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{
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// Initialize Pin Outputs
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// ======================
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// PB0: MOSFET #1 (Peltier)
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DDRB |= (1 << PB0); // Out
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PORTB &= ~(1 << PB0); // Low
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// PB1: MOSFET #2 (Heating)
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DDRB |= (1 << PB1); // Out
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PORTB &= ~(1 << PB1); // Low
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// PB2: MOSFET #3 (Lights)
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DDRB |= (1 << PB2); // Out
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PORTB &= ~(1 << PB2); // Low
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}
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static void SetTWIChannel(int channel)
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{
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unsigned char crb;
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assert(channel >= 0);
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assert(channel <= 3);
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// PCA9546 I2C Multiplexer
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// =======================
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Info("Switching TWI channel to %d...", channel);
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// Excerpts taken from the PCA9546A datasheet:
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// https://www.ti.com/lit/ds/symlink/pca9546a.pdf
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// Following a start condition, the bus master
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// must output the address of the slave it is
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// accessing.
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// 7 6 5 4 | 3 2 1 0
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// 1 1 1 0 | A2 A1 A0 RW
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// FIXED_____ | SELECTABLE____
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TWI_Start(0x70, 0);
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TWI_Wait_ACK();
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// Following the successful acknowledgment of
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// the slave address, the bus master sends a byte
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// which is stored in the control register.
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// 7 6 5 4 | 3 2 1 0
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// X X X X | B3 B2 B1 B0
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// UNUSED____ | CHANNEL_______
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crb = (1 << channel);
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// crb = 0x01; // Channel 0 | 00000001
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// crb = 0x02 // Channel 1 | 00000010
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// crb = 0x04 // Channel 2 | 00000100
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// crb = 0x08 // Channel 3 | 00001000
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TWI_Write(crb);
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// When a channel is selected, the channel
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// becomes active after a stop condition has been
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// placed on the I2C bus. A stop condition always
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// must occur right after the acknowledge cycle.
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TWI_Wait_ACK();
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TWI_Stop();
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Info("TWI channel was switched to %d.", channel);
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}
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