/*
avr_adc.c
- Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
+ Copyright 2008, 2010 Michel Pollet <buserror@gmail.com>
This file is part of simavr.
along with simavr. If not, see <http://www.gnu.org/licenses/>.
*/
-
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "avr_adc.h"
+static avr_cycle_count_t avr_adc_int_raise(struct avr_t * avr, avr_cycle_count_t when, void * param)
+{
+ avr_adc_t * p = (avr_adc_t *)param;
+ if (avr_regbit_get(avr, p->aden)) {
+ // if the interrupts are not used, still raised the UDRE and TXC flag
+ avr_raise_interrupt(avr, &p->adc);
+ avr_regbit_clear(avr, p->adsc);
+ p->first = 0;
+ p->read_status = 0;
+ }
+ return 0;
+}
+
+static uint8_t avr_adc_read_l(struct avr_t * avr, avr_io_addr_t addr, void * param)
+{
+ avr_adc_t * p = (avr_adc_t *)param;
+
+ if (p->read_status) // conversion already done
+ return avr_core_watch_read(avr, addr);
+
+ uint8_t refi = avr_regbit_get_array(avr, p->ref, ARRAY_SIZE(p->ref));
+ uint16_t ref = p->ref_values[refi];
+ uint8_t muxi = avr_regbit_get_array(avr, p->mux, ARRAY_SIZE(p->mux));
+ avr_adc_mux_t mux = p->muxmode[muxi];
+ // optional shift left/right
+ uint8_t shift = avr_regbit_get(avr, p->adlar) ? 6 : 0; // shift LEFT
+
+ uint32_t reg = 0;
+ switch (mux.kind) {
+ case ADC_MUX_SINGLE:
+ reg = p->adc_values[mux.src];
+ break;
+ case ADC_MUX_DIFF:
+ if (mux.gain == 0)
+ mux.gain = 1;
+ reg = ((uint32_t)p->adc_values[mux.src] * mux.gain) -
+ ((uint32_t)p->adc_values[mux.diff] * mux.gain);
+ break;
+ case ADC_MUX_TEMP:
+ reg = p->temp; // assumed to be already calibrated somehow
+ break;
+ case ADC_MUX_REF:
+ reg = mux.src; // reference voltage
+ break;
+ }
+ uint32_t vref = 3300;
+ switch (ref) {
+ case ADC_VREF_VCC:
+ if (!avr->vcc)
+ printf("ADC Warning : missing VCC analog voltage\n");
+ else
+ vref = avr->vcc;
+ break;
+ case ADC_VREF_AREF:
+ if (!avr->aref)
+ printf("ADC Warning : missing AREF analog voltage\n");
+ else
+ vref = avr->aref;
+ break;
+ case ADC_VREF_AVCC:
+ if (!avr->avcc)
+ printf("ADC Warning : missing AVCC analog voltage\n");
+ else
+ vref = avr->avcc;
+ break;
+ default:
+ vref = ref;
+ }
+// printf("ADCL %d:%3d:%3d read %4d vref %d:%d=%d\n",
+// mux.kind, mux.diff, mux.src,
+// reg, refi, ref, vref);
+ reg = (reg * 0x3ff) / vref; // scale to 10 bits ADC
+// printf("ADC to 10 bits 0x%x %d\n", reg, reg);
+ if (reg > 0x3ff) {
+ printf("ADC Warning channel %d clipped %u/%u VREF %d\n", mux.kind, reg, 0x3ff, vref);
+ reg = 0x3ff;
+ }
+ reg <<= shift;
+// printf("ADC to 10 bits %x shifted %d\n", reg, shift);
+ avr->data[p->r_adcl] = reg;
+ avr->data[p->r_adch] = reg >> 8;
+ p->read_status = 1;
+ return avr_core_watch_read(avr, addr);
+}
+
/*
- * PLACEHOLDER ADC MODULE
+ * From Datasheet:
+ * "When ADCL is read, the ADC Data Register is not updated until ADCH is read.
+ * Consequently, if the result is left adjusted and no more than 8-bit
+ * precision is required, it is sufficient to read ADCH.
+ * Otherwise, ADCL must be read first, then ADCH."
+ * So here if the H is read before the L, we still call the L to update the
+ * register value.
*/
+static uint8_t avr_adc_read_h(struct avr_t * avr, avr_io_addr_t addr, void * param)
+{
+ avr_adc_t * p = (avr_adc_t *)param;
+ // no "break" here on purpose
+ switch (p->read_status) {
+ case 0:
+ avr_adc_read_l(avr, p->r_adcl, param);
+ case 1:
+ p->read_status = 2;
+ default:
+ return avr_core_watch_read(avr, addr);
+ }
+}
+
+static void avr_adc_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, void * param)
+{
+ avr_adc_t * p = (avr_adc_t *)param;
+ uint8_t adsc = avr_regbit_get(avr, p->adsc);
+ uint8_t aden = avr_regbit_get(avr, p->aden);
+
+ avr->data[p->adsc.reg] = v;
+
+ // can't write zero to adsc
+ if (adsc && !avr_regbit_get(avr, p->adsc)) {
+ avr_regbit_set(avr, p->adsc);
+ v = avr->data[p->adsc.reg];
+ }
+ if (!aden && avr_regbit_get(avr, p->aden)) {
+ // first conversion
+ p->first = 1;
+ printf("ADC Start AREF %d AVCC %d\n", avr->aref, avr->avcc);
+ }
+ if (aden && !avr_regbit_get(avr, p->aden)) {
+ // stop ADC
+ avr_cycle_timer_cancel(avr, avr_adc_int_raise, p);
+ avr_regbit_clear(avr, p->adsc);
+ }
+ if (!adsc && avr_regbit_get(avr, p->adsc)) {
+ // start one!
+ uint8_t muxi = avr_regbit_get_array(avr, p->mux, ARRAY_SIZE(p->mux));
+ union {
+ avr_adc_mux_t mux;
+ uint32_t v;
+ } e = { .mux = p->muxmode[muxi] };
+ avr_raise_irq(p->io.irq + ADC_IRQ_OUT_TRIGGER, e.v);
+
+ // clock prescaler are just a bit shift.. and 0 means 1
+ uint32_t div = avr_regbit_get_array(avr, p->adps, ARRAY_SIZE(p->adps));
+ if (!div) div++;
+
+ div = avr->frequency >> div;
+ if (p->first)
+ printf("ADC starting at %uKHz\n", div / 13 / 100);
+ div /= p->first ? 25 : 13; // first cycle is longer
+
+ avr_cycle_timer_register(avr,
+ avr_hz_to_cycles(avr, div),
+ avr_adc_int_raise, p);
+ }
+ avr_core_watch_write(avr, addr, v);
+}
+
+static void avr_adc_irq_notify(struct avr_irq_t * irq, uint32_t value, void * param)
+{
+ avr_adc_t * p = (avr_adc_t *)param;
+ avr_t * avr = p->io.avr;
+
+ switch (irq->irq) {
+ case ADC_IRQ_ADC0 ... ADC_IRQ_ADC7: {
+ p->adc_values[irq->irq] = value;
+ } break;
+ case ADC_IRQ_TEMP: {
+ p->temp = value;
+ } break;
+ case ADC_IRQ_IN_TRIGGER: {
+ if (avr_regbit_get(avr, p->adate)) {
+ // start a conversion
+ }
+ } break;
+ }
+}
+
+static void avr_adc_reset(avr_io_t * port)
+{
+ avr_adc_t * p = (avr_adc_t *)port;
+
+ // stop ADC
+ avr_cycle_timer_cancel(p->io.avr, avr_adc_int_raise, p);
+ avr_regbit_clear(p->io.avr, p->adsc);
+
+ for (int i = 0; i < ADC_IRQ_COUNT; i++)
+ avr_irq_register_notify(p->io.irq + i, avr_adc_irq_notify, p);
+}
static avr_io_t _io = {
.kind = "adc",
+ .reset = avr_adc_reset,
};
void avr_adc_init(avr_t * avr, avr_adc_t * p)
avr_register_io(avr, &p->io);
avr_register_vector(avr, &p->adc);
+ // allocate this module's IRQ
+ avr_io_setirqs(&p->io, AVR_IOCTL_ADC_GETIRQ, ADC_IRQ_COUNT, NULL);
-// avr_register_io_write(avr, p->r_eecr, avr_eeprom_write, p);
+ avr_register_io_write(avr, p->r_adcsra, avr_adc_write, p);
+ avr_register_io_read(avr, p->r_adcl, avr_adc_read_l, p);
+ avr_register_io_read(avr, p->r_adch, avr_adc_read_h, p);
}
-
projects / simavr / blobdiff