one_wire: add search impl

Core/Inc/one_wire.h

@@ -14,14 +14,28 @@ typedef struct {
     uint8_t       (*read_dq)(void *handle);
 } onewire_cb_t;
 
+typedef struct {
+    uint8_t rom_num[8];
+} onewire_rom_num_t;
+
+typedef struct {
+    int LastDiscrepancy;
+    int LastFamilyDiscrepancy;
+    int LastDeviceFlag;
+    uint8_t crc8;
+    onewire_rom_num_t rom_num;
+} onewire_search_t;
+
 typedef struct {
     void *user_data;
     onewire_cb_t cb;
+    onewire_search_t _search_state;
 } onewire_t;
 
 uint8_t onewire_bus_reset(onewire_t *ow);
 onewire_ret_t onewire_bus_write_byte(onewire_t *ow, uint8_t byte);
 uint8_t onewire_bus_read_byte(onewire_t *ow);
-onewire_ret_t onewire_bus_search_devices(onewire_t *ow);
+onewire_ret_t onewire_bus_search_init(onewire_t *ow);
+onewire_ret_t onewire_bus_search_nextdev(onewire_t *ow, onewire_rom_num_t *rom);
 
 #endif

Core/Src/main.c

@@ -108,7 +108,13 @@ int main(void)
   /* USER CODE BEGIN 2 */
 
   onewire_bus_reset(&g_ow);
-  onewire_bus_search_devices(&g_ow);
+
+  onewire_rom_num_t rom_num;
+
+  onewire_bus_search_init(&g_ow);
+  while(onewire_bus_search_nextdev(&g_ow, &rom_num)){
+    //register_ow_dev(rom_num);
+  }
 
   /* USER CODE END 2 */
 

Core/Src/one_wire.c

@@ -87,15 +87,19 @@ uint8_t onewire_bus_reset(onewire_t *ow) {
     return device_response ? 0 : 1;
 }
 
+static inline onewire_ret_t onewire_op_write_bit(onewire_t *ow, uint8_t bit) {
+  if(bit) {
+    onewire_op_write_one_bit(ow);
+  }else{
+    onewire_op_write_zero_bit(ow);
+  }
+
+  return OW_OK;
+}
+
 onewire_ret_t onewire_bus_write_byte(onewire_t *ow, uint8_t byte) {
     for(uint8_t i = 0; i < 8; i++) {
-        if(byte & 0x01) {
+        onewire_op_write_bit(ow, byte & 0x01);
-            onewire_op_write_one_bit(ow);
-        }
-        else {
-            onewire_op_write_zero_bit(ow);
-        }
-
         byte >>= 1U;
     }
 
@@ -115,11 +119,197 @@ uint8_t onewire_bus_read_byte(onewire_t *ow) {
     return result;
 }
 
-onewire_ret_t onewire_bus_search_devices(onewire_t *ow) {
+static uint8_t dscrc_table[] = {
-    onewire_bus_write_byte(ow, 0xF0); // Search ROM command.
+        0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
+      157,195, 33,127,252,162, 64, 30, 95,  1,227,189, 62, 96,130,220,
+       35,125,159,193, 66, 28,254,160,225,191, 93,  3,128,222, 60, 98,
+      190,224,  2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
+       70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89,  7,
+      219,133,103, 57,186,228,  6, 88, 25, 71,165,251,120, 38,196,154,
+      101, 59,217,135,  4, 90,184,230,167,249, 27, 69,198,152,122, 36,
+      248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91,  5,231,185,
+      140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
+       17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
+      175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
+       50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
+      202,148,118, 40,171,245, 23, 73,  8, 86,180,234,105, 55,213,139,
+       87,  9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
+      233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
+      116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};
 
-    // Perform a binary search on the bus
+const int FALSE = 0;
+const int TRUE = 1;
 
-    return OW_OK;
+//--------------------------------------------------------------------------
+// Calculate the CRC8 of the byte value provided with the current
+// crc8_state.
+// Returns current crc8_state value
+//
+uint8_t update_crc8(uint8_t *crc8_state, uint8_t value)
+{
+   // See Application Note 27
+
+   // TEST BUILD
+   *crc8_state = dscrc_table[*crc8_state ^ value];
+   return *crc8_state;
 }
 
+//--------------------------------------------------------------------------
+// Init device discovery on the 1-Wire bus
+// Return OW_OK
+//
+onewire_ret_t onewire_bus_search_init(onewire_t *ow)
+{
+   // reset the search state
+   ow->_search_state.LastDiscrepancy = 0;
+   ow->_search_state.LastDeviceFlag = FALSE;
+   ow->_search_state.LastFamilyDiscrepancy = 0;
+
+   return OW_OK;
+}
+
+//--------------------------------------------------------------------------
+// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
+// search state.
+// Return OW_OK    : device found, ROM number in ROM_NO buffer
+//        OW_ERROR : device not found, end of search
+//
+static inline onewire_ret_t onewire_bus_search(onewire_t *ow, onewire_rom_num_t *rom)
+{
+   int id_bit_number;
+   int last_zero, rom_byte_number, search_result;
+   int id_bit, cmp_id_bit;
+   uint8_t rom_byte_mask, search_direction;
+
+   // initialize for search
+   id_bit_number = 1;
+   last_zero = 0;
+   rom_byte_number = 0;
+   rom_byte_mask = 1;
+   search_result = 0;
+   ow->_search_state.crc8 = 0;
+
+   // if the last call was not the last one
+   if (!ow->_search_state.LastDeviceFlag)
+   {
+      // 1-Wire reset
+      if (!onewire_bus_reset(ow))
+      {
+         // reset the search
+         ow->_search_state.LastDiscrepancy = 0;
+         ow->_search_state.LastDeviceFlag = FALSE;
+         ow->_search_state.LastFamilyDiscrepancy = 0;
+         return OW_ERROR;
+      }
+
+      // issue the search command
+      onewire_bus_write_byte(ow, 0xF0);
+
+      // loop to do the search
+      do
+      {
+         // read a bit and its complement
+         id_bit = onewire_op_read_bit(ow);
+         cmp_id_bit = onewire_op_read_bit(ow);
+
+         // check for no devices on 1-wire
+         if ((id_bit == 1) && (cmp_id_bit == 1))
+            break;
+         else
+         {
+            // all devices coupled have 0 or 1
+            if (id_bit != cmp_id_bit)
+               search_direction = id_bit;  // bit write value for search
+            else
+            {
+               // if this discrepancy if before the Last Discrepancy
+               // on a previous next then pick the same as last time
+               if (id_bit_number < ow->_search_state.LastDiscrepancy)
+                  search_direction =
+                    ((ow->_search_state.rom_num.rom_num[rom_byte_number]
+                      & rom_byte_mask) > 0);
+               else
+                  // if equal to last pick 1, if not then pick 0
+                  search_direction =
+                    (id_bit_number == ow->_search_state.LastDiscrepancy);
+
+               // if 0 was picked then record its position in LastZero
+               if (search_direction == 0)
+               {
+                  last_zero = id_bit_number;
+
+                  // check for Last discrepancy in family
+                  if (last_zero < 9)
+                     ow->_search_state.LastFamilyDiscrepancy = last_zero;
+               }
+            }
+
+            // set or clear the bit in the ROM byte rom_byte_number
+            // with mask rom_byte_mask
+            if (search_direction == 1)
+              ow->_search_state.rom_num.rom_num[rom_byte_number]
+                |= rom_byte_mask;
+            else
+              ow->_search_state.rom_num.rom_num[rom_byte_number]
+                &= ~rom_byte_mask;
+
+            // serial number search direction write bit
+            onewire_op_write_bit(ow, search_direction);
+
+            // increment the byte counter id_bit_number
+            // and shift the mask rom_byte_mask
+            id_bit_number++;
+            rom_byte_mask <<= 1;
+
+            // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
+            if (rom_byte_mask == 0)
+            {
+                update_crc8(&ow->_search_state.crc8,
+                  ow->_search_state.rom_num.rom_num[rom_byte_number]);  // accumulate the CRC
+                rom_byte_number++;
+                rom_byte_mask = 1;
+            }
+         }
+      }
+      while(rom_byte_number < 8);  // loop until through all ROM bytes 0-7
+
+      // if the search was successful then
+      if (!((id_bit_number < 65) || (ow->_search_state.crc8 != 0)))
+      {
+         // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
+         ow->_search_state.LastDiscrepancy = last_zero;
+
+         // check for last device
+         if (ow->_search_state.LastDiscrepancy == 0)
+            ow->_search_state.LastDeviceFlag = TRUE;
+
+         search_result = TRUE;
+      }
+   }
+
+   // if no device found then reset counters so next 'search' will be like a first
+   if (!search_result || !ow->_search_state.rom_num.rom_num[0])
+   {
+      ow->_search_state.LastDiscrepancy = 0;
+      ow->_search_state.LastDeviceFlag = FALSE;
+      ow->_search_state.LastFamilyDiscrepancy = 0;
+      search_result = FALSE;
+   }
+   if (search_result){
+     *rom = ow->_search_state.rom_num;
+     return OW_OK;
+   }else{
+     return OW_ERROR;
+   }
+}
+
+//--------------------------------------------------------------------------
+// Find the 'next' devices on the 1-Wire bus
+// Return OW_OK    : device found, ROM number in rom buffer
+//        OW_ERROR : device not found, end of search
+//
+onewire_ret_t onewire_bus_search_nextdev(onewire_t *ow, onewire_rom_num_t *rom)
+{
+   // leave the search state alone
+   return onewire_bus_search(ow, rom);
+}