*
* $LOG$
* 2019/8/28 - ROBIN KRENS
- * PreInitial version
+ * Initial version
*
* $DESCRIPTION$
- * TIMERS, non-blocking...
+ * DS18B20 temperature sensor implementation
+ * Uses the 1-wire protocol. You will need to setup the temperature sensor
+ * with an external pull up resistor. High is the idle state of the chip.
+ * This implementation does not use parasite power. Uses busy waits.
+ * The chip doesn't require too accurate timings. Busy waits are between 15
+ * and 240 microseconds.
+ *
+ * The temperature conversion on the chip it takes a lot longer (up to 700ms).
+ * In case temperature is often read, implementing this with interrupts might be
+ * worthwile.
+ *
+ * Each series of commands is initiated with a long reset and prescence pulse.
+ * Implemented:
+ * - Read ID of Chip
+ * - Convert and read temperature
+ *
+ * TODO:
+ * - Scratchpad copy functionality (+EEPROM)
+ * - Alarm functionality
*
* */
#include <drivers/tsensor.h>
-#define PRESCALER 8 // 1 MHz (1 microsecond)
-#define MAXBUF 10
-
-int cnt;
-enum status { INIT, WAIT_INIT, INIT_DONE } current_status;
-enum rstatus { READ, READ_INIT, READ_DONE } read_status;
-
-static struct {
- uint8_t buf[MAXBUF];
- uint8_t pos;
-} readbuf;
-
-static struct {
- char cmd;
- uint8_t pos;
-} sensor_cmd;
-
-//
-void read_init();
+/* Commands */
+#define READ_ROM 0x33
+#define SKIP_ROM 0xCC
+#define READ_SCRATCH 0xBE
+#define CONVERT_T 0x44
+/* Basic GPIO settings for output pulses and input */
static void in_conf() {
rwrite(GPIOB_CRL, 0x44444444);
}
static void out_conf() {
- rwrite(GPIOB_CRL, 0x46444444); // open drain (with pullup resistor)
-}
-
-/* set preload and generate update event */
-static void timer_config(uint16_t preload) {
- rwrite(TIM4_ARR, preload);
- rsetbit(TIM4_EGR, 0);
-}
-
-static void presence_pulse_conf() {
-
- current_status = INIT;
- out_conf();
- rclrbit(GPIOB_ODR, 6); // low
- timer_config(480); // > 480 us
-}
-
-static void presence_reply_conf() {
-
- current_status = WAIT_INIT;
- in_conf();
- timer_config(60); // > 60 us
-}
-
-static void finish_init() {
- current_status = INIT_DONE;
- timer_config(480);
-}
-
-/* Handlers for read, write and init pulses */
-
-void * write_handler() {
-
-
-
- // i
- // in_conf();
-
-
-
- rclrbit(TIM4_SR1, 0);
- rclrbit(TIM4_SR1, 1);
- if (sensor_cmd.pos < 7) {
-
- if ((sensor_cmd.cmd >> sensor_cmd.pos+1) & 0x01) {
- printf("1\n");
- rwrite(TIM4_CCR1, 5);
- rsetbit(TIM4_EGR, 0);
- }
-
- else {
- printf("0");
- rwrite(TIM4_CCR1, 60);
- rsetbit(TIM4_EGR, 0);
-
- }
- sensor_cmd.pos++;
- }
- else {
-
- read_init();
- }
-
+ rwrite(GPIOB_CRL, 0x46444444); // open drain (with external pullup resistor)
}
-void * reply_handler() {
-
-
- cnt++;
- if (cnt > 16) {
- for(;;);
- }
-
- rclrbit(TIM4_SR1, 0);
- rclrbit(TIM4_SR1, 1);
- switch(read_status) {
- case(READ_INIT):
- in_conf();
- read_status = READ;
- rsetbit(GPIOB_BSRR, 22); // low (<- reset)
- if (rchkbit(GPIOB_IDR, 6)) {
- printf("h\n");
- }
- else {
- printf("l\n");
- }
- timer_config(60);
- break;
- case(READ):
- out_conf();
- rclrbit(GPIOB_ODR, 6); // low
- read_status = READ_INIT;
- timer_config(1);
- break;
- case(READ_DONE):
- // terminate
- break;
- }
-
-
-}
-
-
-void read_init() {
-
-
- rclrbit(TIM4_CR1, 0); // stop
- rclrbit(TIM4_CCER, 0);
- rclrbit(TIM4_CCER, 1);
-
- //rwrite(GPIOB_CRL, 0x46444444); // floating
- out_conf();
- rsetbit(TIM4_CR1, 2); // only overflow generates update
- read_status = READ_INIT;
- timer_config(1); // init 1us
-
- ivt_set_gate(46, reply_handler, 0);
- rsetbit(NVIC_ISER0, 30); // interupt 41 - 32
-
- //rclrbit(TIM4_DIER, 0);
-
- rclrbit(GPIOB_ODR, 6); // low
- rsetbit(TIM4_DIER, 0);
-
- rsetbit(TIM4_CR1, 0);
-
-}
-
-
-void write_init() {
-
- sensor_cmd.cmd = 0x33;
- sensor_cmd.pos = 0;
-
- rsetbit(RCC_APB2ENR, 3); // GPIOB enable
- rsetbit(RCC_APB1ENR, 2); // TIM4 enable
- rsetbitsfrom(TIM4_CR1, 5, 0x00); // edge-aligned mode
- rclrbit(TIM4_CR1, 4); // upcounter (clrbit! not needed to set)
- rsetbit(TIM4_CR1, 2); // only overflow generates update
- rwrite(TIM4_PSC, PRESCALER - 1);
- rwrite(GPIOB_CRL, 0x4A444444);
-
-
- timer_config(61);
-
- if ((sensor_cmd.cmd >> sensor_cmd.pos) & 0x01) {
- printf("1\n");
- rwrite(TIM4_CCR1, 5); // < 15ms
- }
- else {
- printf("0\n");
- rwrite(TIM4_CCR1, 60);
- }
-
- rsetbitsfrom(TIM4_CCMR1, 4, 0x6); // forced high on match
-
- rsetbit(TIM4_CCER, 0);
- rsetbit(TIM4_CCER, 1);
-
- // set write handler
- ivt_set_gate(46, write_handler, 0);
- rsetbit(NVIC_ISER0, 30); // interupt 41 - 32
-
- //rsetbit(TIM4_DIER, 1);
- rsetbit(TIM4_DIER, 0);
- rsetbit(TIM4_CR1, 0);
-
-}
-
-
-void * init_handler() {
-
- switch(current_status) {
- case (INIT):
- printf("M: reset\n");
- presence_reply_conf();
- break;
- case (WAIT_INIT):
- if (!rchkbit(GPIOB_IDR, 6)) {
- printf("S: yes\n");
- }
- else {
- printf("S: no\n");
- }
- finish_init();
- break;
-
- case (INIT_DONE):
- printf("M: fin\n");
- write_init();
- break;
-
- default:
- printf("no status\n");
- }
-
- rclrbit(TIM4_SR1, 0);
-}
-
-/* TODO: write
- * uint8_t cmd = 0x33
- * if (cmd & 0x01)
- * 1 slot
- * else 0 slot
- * cmd = cmd >> 1
- *
- * read, similar as pulse response */
-
-
-void * bare_handler() {
-
-//w2 cnt += 1;
-//w2 printf("CHECKING STATUS\n");
-//w2
-//w2 if(rchkbit(GPIOB_IDR, 6)) {
-//w2 printf("port high\n");
-//w2 }
-//w2 else {
-//w2 printf("port low\n");
-//w2 }
-
-
- cnt += 1;
- printf("Count event %d\n", cnt);
- int switchled = cnt % 2;
- if (switchled) {
- rwrite(GPIOB_CRL, 0x46444444); // open drain general for sensor?
- printf("setting low\n");
- rclrbit(GPIOB_ODR, 6); // low
- }
- else {
- printf("pulling high \n");
- rwrite(GPIOB_CRL, 0x44444444); // open drain general for sensor?
- //rsetbit(GPIOB_ODR, 6); // high
-
- }
- rclrbit(TIM4_SR1, 0);
-}
-
-void send_cmd(unsigned char cmd) {
-
+/* Send command cmd over data wire. Each write slot should be
+ * at least 60ms. */
+static void send_cmd(unsigned char cmd) {
int pos = 0;
for (int i = 0; i < 8; i++) {
+ // initiate write slot
out_conf();
- rclrbit(GPIOB_ODR, 6);
+ rclrbit(GPIOB_ODR, 6); // pull low
+
+ // writing a logical 1 or 0
if ((cmd >> pos) & 0x01) {
_block(5);
in_conf();
_block(60);
- // printf("1");
}
else {
_block(60);
in_conf();
- // printf("0");
}
pos++;
}
}
-void read_reply() {
+/* Read reply of sensor. Depending on the command, the sensor
+ * can send back up to 9 bytes */
+static char get_byte() {
+
+ char c = 0x00;
- for (int i = 0; i < 64; i++) {
+ for (int i = 0; i < 8; i++) {
+ /* Initate write slot*/
out_conf();
rclrbit(GPIOB_ODR, 6);
_block(3);
+ /* Listen for reply */
in_conf();
- if (rchkbit(GPIOB_IDR,6))
- {
- printf("1");
- }
+ if (rchkbit(GPIOB_IDR,6)) {
+ c = c | (0x1 << i);
+ }
else {
- printf("0");
+ c = c | (0x0 << i);
}
+ /* Each read slot should be at least 60 microseconds
+ * before the next one is initiated */
_block(60);
}
-
+ return c;
}
-void tsensor_init() {
+
+/* Initiate the sensor, send a reset pulse and wait consequently for
+ * presence pulse. Slots should be at least 450 and 240 microseconds.
+ * */
+static int tsensor_init() {
rsetbit(RCC_APB2ENR, 3); // GPIOB enable
+
+ /* send presence pulse */
out_conf();
- rclrbit(GPIOB_ODR, 6); // loq
+ rclrbit(GPIOB_ODR, 6); // pull low
_block(450);
+ /* wait for the chips reply */
in_conf();
_block(60);
if (!rchkbit(GPIOB_IDR, 6)) {
- printf("reply");
+ //printf("Info: sensor detected\n");
+ //get_id();
}
else {
- printf("nothing");
+ printf("Error: no temperature sensor found!");
+ return -1;
}
- _block(240);
-
-
-// rsetbit(RCC_APB2ENR, 3); // GPIOB enable
-// rsetbit(RCC_APB1ENR, 2); // TIM4 enable
-//
-// rsetbitsfrom(TIM4_CR1, 5, 0x00); // edge-aligned mode
-// rclrbit(TIM4_CR1, 4); // upcounter (clrbit! not needed to set)
-// rsetbit(TIM4_CR1, 2); // only overflow generates update
-//
-// rwrite(TIM4_PSC, PRESCALER - 1);
-// presence_pulse_conf();
-//// rwrite(TIM4_ARR, preload);
-//// rsetbit(TIM4_EGR, 0);
-//
-// ivt_set_gate(46, init_handler, 0);
-// rsetbit(NVIC_ISER0, 30); // interupt 41 - 32
-//
-////w rsetbit(GPIOB_ODR, 6); //
-// rsetbit(TIM4_DIER, 0);
-// rsetbit(TIM4_CR1, 0); // start
+ _block(240); // finish intialization slot
+
+ return 0;
}
-void wait_for_sensor() {
+
+
+/* Wait for the chip to convert the temperature */
+static void wait_tconvert() {
+
+ printf("Info: Converting temp\n");
+ /* initiate write slot */
out_conf();
rclrbit(GPIOB_ODR, 6);
_block(3);
in_conf();
while (!rchkbit(GPIOB_IDR, 6)) {
- printf("c");
+ //printf(".");
_block(60);
out_conf();
rclrbit(GPIOB_ODR, 6);
}
}
-void run() {
+/* Print some serial and CRC information about the chip */
+void tsensor_printid() {
+
+ tsensor_init();
+ send_cmd(READ_ROM);
+
+ // replies with 8 bytes
+ int nbytes = 8;
- cnt = 0;
-//w2 rsetbit(RCC_APB2ENR, 3);
-//w2 rwrite(GPIOB_CRL, 0x48444444); // input with pull up down
-//w2 tsensor_simple(5000);
+ char scratchbuf[nbytes];
+ memset(&scratchbuf, 0, sizeof(char) * nbytes);
+ scratchbuf[nbytes+1] = '\n';
+
+ for (int i = 0; i < nbytes; i++) {
+ scratchbuf[i] = get_byte();
+ }
+
+
+ printf("Family Code: %#x\n", scratchbuf[0]);
+ printf("Serial Number: 0x");
+ for (int i = 1; i < 7; i++) {
+ printf("%x", scratchbuf[i]);
+ }
+ printf("\n");
+ printf("CRC Code: %#x\n", scratchbuf[7]);
+
+}
- //cnt = 0;
- //rsetbit(RCC_APB2ENR, 3); // GPIOB enable
- //rwrite(GPIOB_CRL, 0x46444444); // open drain general for sensor?
+/* Convert and read temperature of chip. Sensor has to be initialized twice
+ * since there are two series of commands (see datasheet flowchart) */
+uint16_t tsensor_get_temp() {
- //rsetbit(GPIOB_BSRR, 22); // low (<- reset)
+ /* initialize sensor and send commands */
+ tsensor_init();
+ send_cmd(SKIP_ROM);
+ send_cmd(CONVERT_T);
+ wait_tconvert();
tsensor_init();
- send_cmd(0xCC);
- send_cmd(0x44);
- wait_for_sensor();
+ send_cmd(SKIP_ROM);
+ send_cmd(READ_SCRATCH);
- tsensor_init();
- send_cmd(0xCC);
- send_cmd(0xBE);
+ /* Scratchpad is 9 bytes, but we are only interested in
+ * the first two bytes, since they contain the LSB and
+ * MSB of temperature */
+ int nbytes = 2;
+
+ char scratchbuf[nbytes];
+ memset(&scratchbuf, 0, sizeof(char) * nbytes);
+ scratchbuf[nbytes+1] = '\n';
+
+ for (int i = 0; i < nbytes; i++) {
+ scratchbuf[i] = get_byte();
+ }
+
+ // LSB first four bits are after floating point
+ // uint8_t lsb_afltp = scratchbuf[0] & 0xF;
+
+ int8_t lsb_bfltp = (scratchbuf[0] >> 4) & 0xF;
+ // MSB only the first three bits are used
+ uint8_t msb = scratchbuf[1] & 0x7;
+
+ return (msb << 4) + lsb_bfltp;
- //send_cmd(0xCC);
- //send_cmd(0x44);
- //wait_for_sensor();
- //send_cmd(0xBE);
- //wait_for_sensor();
- read_reply();
- //send_cmd(0x33);
- //read_reply();
-// write_init();
-
-// tsensor_output(580, 520);
-// reset();
-// tsensor_simple(580);
}
-//void tsensor_output(uint16_t preload, uint16_t compare/*, uint16_t pulses */) {
-// /* GPIO AND CLOCK */
-// rsetbit(RCC_APB2ENR, 3); // GPIOB enable
-// rwrite(GPIOB_CRL, 0x4A444444); // PB6 for Channel 1 TIM4 alternate
-// rsetbit(RCC_APB1ENR, 2); // TIM4 enable
-//
-// rsetbitsfrom(TIM4_CR1, 5, 0x00); // edge-aligned mode
-// rclrbit(TIM4_CR1, 4); // upcounter (clrbit! not needed to set)
-// rsetbit(TIM4_CR1, 2); // only overflow generates update
-//
-// rwrite(TIM4_PSC, PRESCALER - 1); // 1 MHz
-// rwrite(TIM4_ARR, preload); // preload
-// rwrite(TIM4_CCR1, compare); // compare
-// //rwrite(TIM4_RCR, pulses - 1); /* repeat ONLY IN ADVANCED TIMER */
-//
-// rsetbit(TIM4_EGR, 0); // update generation
-//
-// rsetbit(TIM4_CR1, 3); // one pulse mode
-// rsetbitsfrom(TIM4_CCMR1, 4, 0x6); // mode
-//
-// //rsetbit(TIM4_CCMR1, 3); // preload enable
-// //rsetbit(TIM4_CR1, 7); // buffered
-//
-// rsetbit(TIM4_CCER, 0); // enable output channeli 1
-// rsetbit(TIM4_CCER, 1); // active low
-// rsetbit(TIM4_CR1, 0); // start counter
-//
-// /* INTERRUPTS */
-// ivt_set_gate(46, tmp_update_handler, 0);
-//
-// rsetbit(TIM4_DIER, 1);
-// rsetbit(NVIC_ISER0, 30); // interupt 41 - 32
-//
-//}
+/*
+void test() {
+
+ //get_id();
+ uint16_t temp = get_temp();
+ printf("Current temperature: %d\n", temp);
+
+} */
projects / cortex-from-scratch / commitdiff