1 // DS18B20 Temperature Sensor
7 static volatile u32 ds_dma_buffer;
9 #define DS_PORT THERMO_GPIO_Port
10 #define DS_PIN THERMO_GPIO_Pin
11 #define DS_PIN_MASK (1U << 7) // Unfortunately, this cannot be inferred from the Pin constant
13 #define DS_DMA_CHANNEL LL_DMA_CHANNEL_6
17 #define DEBUG debug_printf
19 #define DEBUG(xxx, ...) do { } while (0)
22 static void ds_reset(void)
24 DEBUG("DS18B20: Reset\n");
25 LL_TIM_DisableCounter(TIM3);
26 LL_TIM_SetOnePulseMode(TIM3, LL_TIM_ONEPULSEMODE_SINGLE);
28 // DMA for reading pin state
29 ds_dma_buffer = 0xdeadbeef;
30 LL_DMA_SetMemoryAddress(DS_DMA, DS_DMA_CHANNEL, (u32) &ds_dma_buffer);
31 LL_DMA_SetPeriphAddress(DS_DMA, DS_DMA_CHANNEL, (u32) &DS_PORT->IDR);
32 LL_DMA_SetDataLength(DS_DMA, DS_DMA_CHANNEL, 1);
33 LL_DMA_EnableChannel(DS_DMA, DS_DMA_CHANNEL);
35 LL_TIM_OC_InitTypeDef oc;
37 // CC1 is used to drive the DMA (read line state at specified time)
38 LL_TIM_OC_StructInit(&oc);
39 oc.OCMode = LL_TIM_OCMODE_FROZEN;
40 oc.CompareValue = 560;
41 LL_TIM_OC_Init(TIM3, LL_TIM_CHANNEL_CH1, &oc);
42 LL_TIM_EnableDMAReq_CC1(TIM3);
43 LL_TIM_CC_SetDMAReqTrigger(TIM3, LL_TIM_CCDMAREQUEST_CC);
45 // CC2 is used to generate pulses (return line to idle state at specified time)
46 LL_TIM_OC_StructInit(&oc);
47 oc.OCMode = LL_TIM_OCMODE_FORCED_ACTIVE;
48 oc.OCState = LL_TIM_OCSTATE_ENABLE;
49 oc.CompareValue = 480;
50 oc.OCPolarity = LL_TIM_OCPOLARITY_LOW;
51 LL_TIM_OC_Init(TIM3, LL_TIM_CHANNEL_CH2, &oc);
53 // Set timer period to the length of the whole transaction
54 LL_TIM_SetAutoReload(TIM3, 999);
56 // Pull line down and start timer
57 LL_TIM_OC_SetMode(TIM3, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_INACTIVE);
58 LL_TIM_EnableCounter(TIM3);
60 // Wait until the timer expires
61 while (LL_TIM_IsEnabledCounter(TIM3))
63 // Counter is automatically disabled at the end of cycle
66 LL_TIM_DisableDMAReq_CC1(TIM3);
67 LL_DMA_DisableChannel(DS_DMA, DS_DMA_CHANNEL);
69 DEBUG("Init DMA: %08x [%u] (%u remains)\n", ds_dma_buffer, !!(ds_dma_buffer & DS_PIN_MASK), LL_DMA_GetDataLength(DS_DMA, DS_DMA_CHANNEL));
72 static void ds_send_byte(byte b)
74 DEBUG("DS write: %02x\n", b);
75 LL_TIM_SetAutoReload(TIM3, 99); // Each write slot takes 100μs
76 for (uint m=1; m < 0x100; m <<= 1)
78 LL_TIM_OC_SetCompareCH2(TIM3, ((b & m) ? 1 : 89)); // 1: 1μs pulse, 0: 89μs pulse
79 LL_TIM_OC_SetMode(TIM3, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_FORCED_ACTIVE);
80 LL_TIM_OC_SetMode(TIM3, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_INACTIVE);
81 LL_TIM_EnableCounter(TIM3);
82 while (LL_TIM_IsEnabledCounter(TIM3))
87 static byte ds_recv_byte(void)
89 LL_TIM_SetAutoReload(TIM3, 79); // Each read slot takes 80μs
90 LL_TIM_OC_SetCompareCH2(TIM3, 1); // Generate 1μs pulse to start read slot
91 LL_TIM_OC_SetCompareCH1(TIM3, 8); // Sample data 8μs after start of slot
92 LL_TIM_EnableDMAReq_CC1(TIM3);
95 for (uint m=1; m < 0x100; m <<= 1)
97 ds_dma_buffer = 0xdeadbeef;
98 LL_DMA_SetDataLength(DS_DMA, DS_DMA_CHANNEL, 1);
99 LL_DMA_EnableChannel(DS_DMA, DS_DMA_CHANNEL);
100 LL_TIM_OC_SetMode(TIM3, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_FORCED_ACTIVE);
101 LL_TIM_OC_SetMode(TIM3, LL_TIM_CHANNEL_CH2, LL_TIM_OCMODE_INACTIVE);
102 LL_TIM_EnableCounter(TIM3);
103 while (LL_TIM_IsEnabledCounter(TIM3))
105 debug_printf("XXX %08x\n", ds_dma_buffer);
106 if (ds_dma_buffer & DS_PIN_MASK)
108 LL_DMA_DisableChannel(DS_DMA, DS_DMA_CHANNEL);
111 LL_TIM_DisableDMAReq_CC1(TIM3);
112 DEBUG("DS read: %02x\n", out);
116 static byte ds_buf[10];
118 static int ds_recv_block(uint n)
121 for (uint i=0; i<n; i++)
123 uint b = ds_recv_byte();
125 for (uint j=0; j<8; j++)
127 uint k = (b & 1) ^ (crc >> 7);
128 crc = (crc << 1) & 0xff;
137 debug_printf("WARNING: Invalid CRC %02x\n", crc);
147 debug_puts("Init\n");
148 NVIC_DisableIRQ(TIM3_IRQn); // One day, we will handle everything from interrupts...
157 // FIXME: Configure precision
161 LL_GPIO_ResetOutputPin(LED_GPIO_Port, LED_Pin);
162 // debug_printf("Tick tock: %d\n", cnt);
168 while (ds_recv_byte() != 0xff)
176 int t = (int16_t)(ds_buf[0] | (ds_buf[1] << 8));
179 LL_GPIO_SetOutputPin(LED_GPIO_Port, LED_Pin);
180 debug_printf("Temp: %d.%03d degC\n", t/1000, t%1000);