Alastair D'Silva / DS1820

A cut-down version of https://os.mbed.com/users/Sissors/code/DS1820/ tweaked for use with the STM32F103. It is all generic Mbed operations though, so should be usable anywhere. Non-essential functions have been removed, as this is intended for use within a tutorial.

Dependencies:   LinkedList

Dependents:   STM32F103C8T6_DS18B20 stm32f103c8t6-ds18b20

Fork of DS1820 by Erik -

Diff: DS1820.cpp

Revision:
17:045f96704cc6
Parent:
16:d490e11c466d
Child:
18:3a24aedc1e7c
Child:
19:b9d69bad8185
--- a/DS1820.cpp	Thu Jan 11 04:37:42 2018 +0000
+++ b/DS1820.cpp	Fri Jan 12 00:38:01 2018 +0000
@@ -1,10 +1,7 @@
 #include "DS1820.h"
 
-DigitalOut tracer(PA_6);
-
 static inline void onewire_input(DigitalInOut &pin) {
     pin.input();
-    pin.mode(PullUp);
 }
 
 static inline void onewire_output(DigitalInOut &pin) {
@@ -60,18 +57,15 @@
 void DS1820::onewire_bit_out (bool bit_data) {
     onewire_output(_datapin);
     wait_us(1);                 // DXP modified from 5
-    if (bit_data) {
-        onewire_input(_datapin); // bring data line high
-    } else {
-        wait_us(57);            // keep data line low
-        onewire_input(_datapin);
+    if (!bit_data) {
+         wait_us(57);            // keep data line low
     }
-        wait_us(55);
+    onewire_input(_datapin);
+    wait_us(50);
 }
  
 void DS1820::onewire_byte_out(char data) { // output data character (least sig bit first).
-    int n;
-    for (n=0; n<8; n++) {
+    for (int n=0; n<8; n++) {
         onewire_bit_out(data & 0x01);
         data = data >> 1; // now the next bit is in the least sig bit position.
     }
@@ -276,30 +270,17 @@
  
 int DS1820::convertTemperature(bool wait, devices device) {
     // Convert temperature into scratchpad RAM for all devices at once
-    int delay_time = 750; // Default delay time
-    char resolution;
+    int delay_time = 850; // Default delay time
     if (device==all_devices)
         skip_ROM();          // Skip ROM command, will convert for ALL devices
     else {
         match_ROM();
-        if ((FAMILY_CODE == FAMILY_CODE_DS18B20 ) || (FAMILY_CODE == FAMILY_CODE_DS1822 )) {
-            resolution = RAM[4] & 0x60;
-            if (resolution == 0x00) // 9 bits
-                delay_time = 94;
-            if (resolution == 0x20) // 10 bits
-                delay_time = 188;
-            if (resolution == 0x40) // 11 bits. Note 12bits uses the 750ms default
-                delay_time = 375;
-        }
     }
     
-    tracer = 0;    
-    onewire_byte_out( 0x44);  // perform temperature conversion
-    tracer = 1;
+    onewire_byte_out(0x44);  // perform temperature conversion
     
     if (wait) {
         wait_ms(delay_time);
-        delay_time = 0;
     }
     return delay_time;
 }
@@ -314,8 +295,9 @@
     for(i=0;i<9;i++) {
         RAM[i] = onewire_byte_in();
     }
-//    if (!RAM_checksum_error())
-//       crcerr = 1;
+    printf("Scratchpad=%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\r\n",
+        RAM[8], RAM[7], RAM[6], RAM[5], RAM[4], RAM[3], RAM[2], RAM[1], RAM[0]);
+    printf("Checksum is %s\r\n", RAM_checksum_error() ? "bad" : "good");
 }
 
 bool DS1820::setResolution(unsigned int resolution) {