File content as of revision 7:024ace6d943c:

#include    "mbed.h"
#include  "1-wire.h"
#include     "log.h"
#include      "io.h"
#include    "wifi.h"
#include "ds18b20.h"

#define DEBUG false //Set this to true to add debug messages to the log

#define DEVICE_MAX 4

#define SEND_BUFFER_LENGTH 10
#define RECV_BUFFER_LENGTH 10
static char send[SEND_BUFFER_LENGTH];
static char recv[RECV_BUFFER_LENGTH];
static int sendlen = 0;
static int recvlen = 0;

int     DS18B20DeviceCount = 0;
char    DS18B20DeviceList[DEVICE_MAX * 8];
int16_t DS18B20Value[DEVICE_MAX];

int16_t DS18B20ValueFromRom(char* rom)
{
    for (int device = 0; device < DS18B20DeviceCount; device++) if (memcmp(DS18B20DeviceList + 8 * device, rom, 8) == 0) return DS18B20Value[device];
    return DS18B20_ERROR_NOT_FOUND;
}
char rom[8];
int allRomsFound = false;
static void searchRom(int first)
{
    sendlen = 1;
    send[0] = 0xF0; //Search Rom
    recvlen = 0;
    for (int i = 0; i < recvlen; i++) recv[i] = 0;
    if (first)  OneWireSearch(send[0], rom, &allRomsFound);
    else        OneWireSearch(send[0], NULL, NULL);
}
static void readScratchpad(int device)
{   
    sendlen = 10;
    send[0] = 0x55; //Match Rom
    for (int i = 0; i < 8; i++) send[i+1] = DS18B20DeviceList[device * 8 + i];
    send[9] = 0xBE; //Read Scratchpad
    recvlen = 9;
    for (int i = 0; i < recvlen; i++) recv[i] = 0;
    OneWireExchange(sendlen, recvlen, send, recv, 0);
}
static void convertT()
{
    sendlen = 2;
    send[0] = 0xCC; //Skip Rom
    send[1] = 0x44; //Convert T
    recvlen = 0;
    for (int i = 0; i < recvlen; i++) recv[i] = 0;
    OneWireExchange(sendlen, recvlen, send, recv, 750);
}
#define IDLE                0
#define LIST_FIRST_DEVICE   1
#define LIST_NEXT_DEVICE    2
#define CONVERT_T           3
#define READ_SCRATCH_PAD    4
#define EXTRACT_TEMPERATURE 5
static volatile int state = IDLE;
int DS18B20Busy() { return state; }
static int handlestate()
{
    if (OneWireBusy()) return 0;
    static int device;
    switch (state)
    {
        case IDLE:
            state = LIST_FIRST_DEVICE;
            break;
        case LIST_FIRST_DEVICE:
            device = 0;
            searchRom(true);
            state = LIST_NEXT_DEVICE;
            break;
        case LIST_NEXT_DEVICE:
            if (OneWireResult())
            {
                state = IDLE;
            }
            else
            {
                for (int i = 0; i < 8; i++) DS18B20DeviceList[8 * device + i] = rom[i];
                device++;
                if (allRomsFound || device >= DEVICE_MAX)
                {
                    DS18B20DeviceCount = device;
                    state = CONVERT_T;
                }
                else
                {
                    searchRom(false);
                }
            }
            break;            
        case CONVERT_T:
            if (OneWireResult())
            {
                state = IDLE;
            }
            else
            {
                convertT();
                device = 0;
                state = READ_SCRATCH_PAD;
            }
            break;
        case READ_SCRATCH_PAD:
            if (OneWireResult())
            {
                state = IDLE;
            }
            else
            {
                readScratchpad(device);
                state = EXTRACT_TEMPERATURE;
            }
            break;
        case EXTRACT_TEMPERATURE:
            switch (OneWireResult())
            {
                case ONE_WIRE_RESULT_OK:
                    DS18B20Value[device] = recv[1];
                    DS18B20Value[device] <<= 8;
                    DS18B20Value[device] |= recv[0];
                    break;
                case ONE_WIRE_RESULT_CRC_ERROR:               DS18B20Value[device] = DS18B20_ERROR_CRC;                     break;
                case ONE_WIRE_RESULT_NO_DEVICE_PRESENT:       DS18B20Value[device] = DS18B20_ERROR_NO_DEVICE_PRESENT;       break;
                case ONE_WIRE_RESULT_TIMED_OUT:               DS18B20Value[device] = DS18B20_ERROR_TIMED_OUT;               break;            
                case ONE_WIRE_RESULT_NO_DEVICE_PARTICIPATING: DS18B20Value[device] = DS18B20_ERROR_NO_DEVICE_PARTICIPATING; break;
                default:
                    LogF("Unknown OneWireResult %d\r\n", OneWireResult());
                    break;
            }
            device++;
            if (device < DS18B20DeviceCount) state = READ_SCRATCH_PAD;
            else                             state = IDLE;
            break;
        default:
            LogF("Unknown DS18B20 state %d\r\n", state);
            return -1;
    }
    return 0;
}
static void logcomms()
{
    static int wasbusy = false;
    if (!OneWireBusy() && wasbusy)
    {
        LogF("1-wire | send:");
        for (int i = 0; i < sendlen; i++) LogF(" %02x", send[i]);
        LogF(" | recv:");
        for (int i = 0; i < recvlen; i++) LogF(" %02x", recv[i]);
        LogF("\r\n");
    }
    wasbusy = OneWireBusy();
}
int DS18B20Init()
{
    return 0;
}
int DS18B20Main()
{
    
    if (DEBUG) logcomms();
    
    int r = handlestate(); if (r) return -1;
    
    return 0;
}