diff --git a/Makefile b/Makefile
index 35d4790ad421501f0fe53f1cc125cfdb4af6d78c..826ec6ba8c9578d1d1a41e7d75cf0a67bf46e8cf 100644
--- a/Makefile
+++ b/Makefile
@@ -25,10 +25,10 @@ clean:
rm -f $(TARGET).elf *.o *.hex
%.o: %.c
- $(GCC_BIN) -c $(C_FLAGS) $< -o $@
+ $(GCC_BIN) -c $(C_FLAGS) *.c
$(TARGET).elf: $(TARGET).o
- $(GCC_BIN) $(LD_FLAGS) $(TARGET).o -o $(TARGET).elf
+ $(GCC_BIN) $(LD_FLAGS) *.o -o $(TARGET).elf
$(TARGET).hex: $(TARGET).elf
$(OBJCOPY_BIN) $(OBJCOPY_FLAGS) $(TARGET).elf $(TARGET).hex
diff --git a/ads8698.c b/ads8698.c
new file mode 100644
index 0000000000000000000000000000000000000000..0591f2ce367844dc605165ce2b2eaf8401e75324
--- /dev/null
+++ b/ads8698.c
@@ -0,0 +1,75 @@
+/**
+ * This file includes functions for interacting with an ADC
+ *
+ * Written for: TI ADS8698 8-channel ADC
+ *
+ * Connections:
+ * Function | ADC Pin | AVR Port | Pin # on DIP Atmega328P
+ * ----------+-------------+------------+-------------------------
+ * Data In | 1 (SDI) | PB3 (MOSI) | 17
+ * Reset | 2 (RST) | PC0 | 23
+ * Data Out | 36 (SDO) | PB4 (MISO) | 18
+ * Clock | 37 (SCLK) | PB5 (SCK) | 19
+ * Chip Sel.| 38 (CS) | PC1 | 24
+ */
+
+#include <avr/io.h>
+#include <util/delay.h>
+
+#include "include/spi.h"
+#include "include/ads8698.h"
+
+/* Initialize the ADC. */
+void ADS8698_init(void) {
+
+ // Start SPI.
+ SPI_init();
+
+ // Set RST and CS as outputs.
+ DDRC |= (1<<DDC0) | (1<<DDC1);
+
+ // Pull RST and CS high.
+ PORTC |= _BV(PORTC0);
+ PORTC |= _BV(PORTC1);
+
+ // Reset the ADC.
+ ADS8698_reset();
+
+ // Start measurements
+ ADS8698_send_command(ADS8698_RESET);
+ SPI_transmit('H');
+ SPI_transmit('e');
+ SPI_transmit('l');
+ SPI_transmit('l');
+ SPI_transmit('o');
+ SPI_transmit('!');
+}
+
+/* Set the input range on the ADC. */
+void ADS8698_set_range(ADS8698_range range) {
+ // TODO
+ return;
+}
+
+/* Write to a register on the ADC. */
+void ADS8698_write_register(uint8_t address, uint8_t data) {
+ // TODO
+ return;
+}
+
+/* Send a command to the ADC. */
+void ADS8698_send_command(ADS8698_command command) {
+ // TODO
+ return;
+}
+
+/* Reset the ADC.
+ *
+ * Pull RST low for 70ns (instructions: 40-100ns).
+ * See datasheet section 8.4.1.1.6.
+ */
+void ADS8698_reset(void) {
+ PORTC &= ~_BV(PORTC0);
+ _delay_us(0.47);
+ PORTC |= _BV(PORTC0);
+}
diff --git a/blink.c b/blink.c
deleted file mode 100644
index a1c46b21deaddc45243fbae2387215ce66951b66..0000000000000000000000000000000000000000
--- a/blink.c
+++ /dev/null
@@ -1,38 +0,0 @@
-#include <avr/io.h>
-#include <util/delay.h>
-
-#define STROBE_DURATION_MS 20
-
-/* This file is just placeholder stuff. It has nothing to do with testing. */
-
-void delay(int duration) {
- duration = duration / 10;
- while (duration--) {
- _delay_ms(10);
- }
-}
-
-void blink_once(int duration) {
- /* Output High */
- PORTB |= _BV(PORTB5);
-
- /* Wait */
- delay(duration);
-
- /* Output Low */
- PORTB &= ~_BV(PORTB5);
-}
-
-void strobe_pulse() {
- /* Blinking pattern. Looks neat. */
- for (int j = 5; j < 10; j++) {
- for (int i = 1; i < j; i++) {
- blink_once(STROBE_DURATION_MS * i);
- delay(STROBE_DURATION_MS * i);
- }
- for (int i = j; i > 0; i--) {
- blink_once(STROBE_DURATION_MS * i);
- delay(STROBE_DURATION_MS * i);
- }
- }
-}
diff --git a/include/ads8698.h b/include/ads8698.h
new file mode 100644
index 0000000000000000000000000000000000000000..293a92d16b5ea2e96eaf337b314669c199bb17ab
--- /dev/null
+++ b/include/ads8698.h
@@ -0,0 +1,62 @@
+/**
+ * This file includes functions for interacting with an ADC
+ *
+ * Written for: TI ADS8698 8-channel ADC
+ *
+ * Connections:
+ * Function | ADC Pin | AVR Port | Pin # on DIP Atmega328P
+ * ----------+-------------+------------+-------------------------
+ * Data In | 1 (SDI) | PB3 (MOSI) | 17
+ * Reset | 2 (RST) | PC0 | 23
+ * Data Out | 36 (SDO) | PB4 (MISO) | 18
+ * Clock | 37 (SCLK) | PB5 (SCK) | 19
+ * Chip Sel.| 38 (CS) | PC1 | 24
+ */
+
+
+/* ADC Commands.
+ *
+ * See datasheet section 8.5.1.
+ */
+typedef enum {
+ ADS8698_NO_OP = 0x00, // Continue operating in previous mode.
+ ADS8698_STANDBY = 0x82, // Enter standby mode.
+ ADS8698_POWER_DOWN = 0x83, // Power down.
+ ADS8698_RESET = 0x85, // Reset.
+ ADS8698_AUTO_RESET = 0xA0, // Reset and enter auto-scan mode.
+ ADS8698_MANUAL_CH0 = 0xC0, // Select channel 0 input.
+ ADS8698_MANUAL_CH1 = 0xC4, // Select channel 1 input.
+ ADS8698_MANUAL_CH2 = 0xC8, // Select channel 2 input.
+ ADS8698_MANUAL_CH3 = 0xCC, // Select channel 3 input.
+ ADS8698_MANUAL_CH4 = 0xD0, // Select channel 4 input.
+ ADS8698_MANUAL_CH5 = 0xD4, // Select channel 5 input.
+ ADS8698_MANUAL_CH6 = 0xD8, // Select channel 6 input.
+ ADS8698_MANUAL_CH7 = 0xDC, // Select channel 7 input.
+ ADS8698_MANUAL_AUX = 0xE0, // Select aux input.
+} ADS8698_command;
+
+
+/* ADC Input Ranges.
+ *
+ * See datasheet section 8.5.2.3.3.
+ */
+typedef enum {
+ ADS8698_RANGE_BIPOLAR_2_5X = 0x00, // 0 +/- 2.5 x Vref
+ ADS8698_RANGE_BIPOLAR_1_25X = 0x01, // 0 +/- 1.25 x Vref
+ ADS8698_RANGE_BIPOLAR_0_625X = 0x02, // 0 +/- 0.625 x Vref
+ ADS8698_RANGE_UNIPOLAR_2_5X = 0x05, // 0 + 2.5 x Vref
+ ADS8698_RANGE_UNIPOLAR_1_25X = 0x0 // 0 + 1.25 x Vref
+} ADS8698_range;
+
+
+/* Initialize the ADC. */
+void ADS8698_init(void);
+
+/* Set the input range on the ADC. */
+void ADS8698_set_range(ADS8698_range range);
+
+/* Send a command to the ADC. */
+void ADS8698_send_command(ADS8698_command command);
+
+/* Reset the ADC. */
+void ADS8698_reset(void);
diff --git a/include/measure.h b/include/measure.h
new file mode 100644
index 0000000000000000000000000000000000000000..c3af59e94b60763f4959b8bb196ceb7a5296f9f2
--- /dev/null
+++ b/include/measure.h
@@ -0,0 +1,16 @@
+/**
+ * This file includes functions for measuring electrical resistance.
+ */
+
+typedef struct Measurements Measurements;
+
+struct Measurements {
+ double value1, value2, value3, value4, value5, value6, value7, value8;
+};
+
+
+/* Prepare for measuring resistance. */
+void Measure_init(void);
+
+/* Acquire resistance measurements. */
+struct Measurements measure(void);
diff --git a/include/spi.h b/include/spi.h
new file mode 100644
index 0000000000000000000000000000000000000000..5bf901f56b55f64895cf477a87980c250c7d1f81
--- /dev/null
+++ b/include/spi.h
@@ -0,0 +1,12 @@
+/**
+ * Logic for using SPI to communicate between the AVR and other devices.
+ */
+
+/* Initialize the microcontroller's SPI interface. */
+void SPI_init(void);
+
+/* Send a byte over the SPI interface. */
+void SPI_transmit(char data);
+
+/* Receive a byte from the SPI interface. */
+char SPI_receive(void);
diff --git a/main.c b/main.c
index 5efeeb9abe3d85dff8666d7cb36d0c89fa625c05..70d39b1b0e3469f8daea65800d50716e5ab096cb 100644
--- a/main.c
+++ b/main.c
@@ -1,13 +1,22 @@
-#include "blink.c"
+#include "include/measure.h"
+/* Start-up procedure */
void init() {
- /* Make Pin 5 of PORTB an output. */
- DDRB |= _BV(DDB5);
+ /* Activate display. */
+ // TODO
+
+ /* Prepare ADC for measurements. */
+ Measure_init();
}
+/* Main code; will repeat forever */
void loop() {
- /* Strobe forever */
- strobe_pulse();
+ /* Measure resistance. */
+ // TODO
+ Measure_init();
+
+ /* Update display. */
+ // TODO
}
int main(void) {
diff --git a/measure.c b/measure.c
new file mode 100644
index 0000000000000000000000000000000000000000..c14a95b748807cf6e112f4ed9eae902a8fa8bcfb
--- /dev/null
+++ b/measure.c
@@ -0,0 +1,28 @@
+/**
+ * This file includes functions for measuring electrical resistance.
+ */
+
+#include <avr/io.h>
+#include <util/delay.h>
+
+#include "include/spi.h"
+#include "include/ads8698.h"
+#include "include/measure.h"
+
+
+
+/* Acquire resistance measurements. */
+struct Measurements measure() {
+ /* Do the stuff. */
+ // TODO
+ return (Measurements) {1, 1, 1, 1, 1, 1, 1, 1};
+}
+
+
+/* Prepare for measuring resistance. */
+void Measure_init(void) {
+ ADS8698_init();
+ _delay_us(100);
+ // int sample_count = 2048; // TODO: what is this
+ // ADS8698_config(&sample_buffer, sample_count, ADS8698_CHANNEL_0, INPUT_RANGE_UNIPOLAR_1_25X_VREF);
+}
diff --git a/spi.c b/spi.c
new file mode 100644
index 0000000000000000000000000000000000000000..e20d0c6a8cf562365c676f31e84404b0867a36ca
--- /dev/null
+++ b/spi.c
@@ -0,0 +1,36 @@
+/**
+ * Logic for using SPI to communicate between the AVR and other devices.
+ */
+
+#include <avr/io.h>
+
+#include "include/spi.h"
+
+/* Initialize the microcontroller's SPI interface. */
+void SPI_init(void) {
+ // Set MOSI, SCK, and SS as outputs
+ DDRB = (1<<DDB3) | (1<<DDB5) | (1<<DDB2);
+
+ // Enable SPI, become master, set clock rate to CPU clock / 16.
+ SPCR = (1<<SPE) | (1<<MSTR);
+}
+
+/* Send a byte over the SPI interface. */
+void SPI_transmit(char data) {
+ // Put the data in the SPI Data Register.
+ SPDR = data;
+
+ // Wait for transmission to complete.
+ while(!(SPSR & (1<<SPIF)))
+ ;
+}
+
+/* Receive a byte from the SPI interface. */
+char SPI_receive(void) {
+ // Wait for reception to complete.
+ while (!(SPSR & (1<<SPIF)))
+ ;
+
+ // Return received value from data register.
+ return SPDR;
+}