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m05e00 values ok prescaler and 8bits

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hugo LAMY
2025-03-14 14:15:49 +01:00
parent 847f969a53
commit 6ef217c05e
3 changed files with 19 additions and 9 deletions
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2
.vscode/settings.json vendored
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@@ -1,4 +1,6 @@
{ {
"editor.insertSpaces": false,
"editor.detectIndentation": false,
"files.associations": { "files.associations": {
"io.h": "c", "io.h": "c",
"delay.h": "c", "delay.h": "c",

5
module05/ex00/adc.c
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@@ -19,9 +19,8 @@ void adc_init(uint8_t prescaler_value) {
uint16_t adc_read(uint8_t channel) { uint16_t adc_read(uint8_t channel) {
CLEAR(PRR, PRADC); // 24.3 : ensure power reduction is disabled for ADC, (10.11.3 : PRR – Power Reduction Register) CLEAR(PRR, PRADC); // 24.3 : ensure power reduction is disabled for ADC, (10.11.3 : PRR – Power Reduction Register)
ADMUX = (ADMUX & 0b11110000) | (channel & 0b1111); // Table 24-4 : Select ADC channel, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0) ADMUX = (ADMUX & 0b11110000) | (channel & 0b1111); // Table 24-4 : Select ADC channel, (Table 14-6 : alternate function for RV1 on PC0 -> ADC0)
// ADMUX |= (1 << ADLAR); // 24.9.3 : enable left adjust result ADMUX |= (1 << ADLAR); // 24.9.1 : enable left adjust result
ADCSRA |= (1 << ADSC); // 24.9.2 : Start conversion, ADSC: ADC Start Conversion ADCSRA |= (1 << ADSC); // 24.9.2 : Start conversion, ADSC: ADC Start Conversion
while (ADCSRA & (1 << ADSC)); // Wait for completion while (ADCSRA & (1 << ADSC)); // Wait for completion
// return ADCH; // 24.9.3 : ADC updated only when ADCH is read, not ADCL, so for 8 bits precision uses left adjust result to only read ADCH return ADCH; // 24.9.3 : ADC updated only when ADCH is read, not ADCL, so for 8 bits precision uses left adjust result to only read ADCH
return ADC;
} }

21
module05/ex00/main.c
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@@ -2,10 +2,19 @@
// 1.1.7 : AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6 // 1.1.7 : AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6
// 1.1.8 : AREF is the analog reference pin for the A/D Converter // 1.1.8 : AREF is the analog reference pin for the A/D Converter
// 24.4 : frequency needs to be between 50kHz and 200kHz, for less than 10bits accuracy it can be >200kHz
// -> Frequence_ADC = Frequance_CPU / Prescaler (Fadc = Fcpu/P):
// - P = 2 -> Fadc = 16,000,000 / 2 = 8,000,000 = 8MHz
// - P = 4 -> Fadc = 16,000,000 / 4 = 4,000,000 = 4MHz
// - P = 8 -> Fadc = 16,000,000 / 8 = 2,000,000 = 2MHz
// - P = 16 -> Fadc = 16,000,000 / 16 = 1,000,000 = 1MHz
// - P = 32 -> Fadc = 16,000,000 / 32 = 500,000 = 500KHz
// - P = 64 -> Fadc = 16,000,000 / 64 = 250,000 = 250KHz -> OK
// - P = 128 -> Fadc = 16,000,000 / 128 = 125,000 = 125KHz -> OK
#define ADC_PRESCALER 2 #define ADC_PRESCALER 64 // Table 24-5 : can only be 2, 4, 8, 16, 32, 64, or 128
void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits) { // num_digits : number of digit of the output, ex 2 for 3FF (1023) -> FF void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits) { // num_digits : number of digit of the output, ex 2 for 3FF (1023) -> FF
for (uint8_t i = 0; i < num_digits; ++i) { for (uint8_t i = 0; i < num_digits; ++i) {
uint8_t shift = (num_digits - 1 - i) * 4; uint8_t shift = (num_digits - 1 - i) * 4;
out[i] = INT_TO_HEX_CHAR((value >> shift) & 0x0F); out[i] = INT_TO_HEX_CHAR((value >> shift) & 0x0F);
@@ -16,15 +25,15 @@ void int_to_hex_string(uint64_t value, char *out, uint8_t num_digits) { // nu
// description // description
int main() { int main() {
char buffer[4]; char buffer[4];
SREG |= ENABLE_GLOBAL_INTERRUPT; // 7.3.1 : Status Register, bit 7 : I – Global Interrupt Enable SREG |= ENABLE_GLOBAL_INTERRUPT; // 7.3.1 : Status Register, bit 7 : I – Global Interrupt Enable
uart_init(); uart_init();
adc_init(ADC_PRESCALER); adc_init(ADC_PRESCALER);
while(1) { while(1) {
uint16_t value = adc_read(0); // Read from ADC0 (A0) uint16_t value = adc_read(0); // Read from ADC0 (A0)
int_to_hex_string(value, buffer, 3); int_to_hex_string(value, buffer, 2);
uart_printstr_endl(buffer); uart_printstr_endl(buffer);
_delay_ms(20); // Wait 20ms _delay_ms(20); // Wait 20ms
} }
} }