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| en:examples:sensor:1-wire [2012/06/06 19:21] – raivo.sell | en:examples:sensor:1-wire [2020/07/20 09:00] (current) – external edit 127.0.0.1 | ||
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| - | ====== 1-wire temperature sensor | + | ====== 1-wire temperature sensor ====== |
| //The necessary knowledge: [HW] [[en: | //The necessary knowledge: [HW] [[en: | ||
| [HW] [[en: | [HW] [[en: | ||
| Line 5: | Line 6: | ||
| ===== Theory ===== | ===== Theory ===== | ||
| - | ==== 1-wire protocol ==== | + | [{{ : |
| - | [{{ : | + | |
| Dallas Semiconductor Corp. worked out a communication bus system for simple sensors and other equipments called 1-wire protocol. This protocol provides low-speed data exchange, signaling and power over single signal wire. It is possible to connect up to 75 devices to one bus, forming MicroLan networks. MicroLan networks have one master unit, what controls network' | Dallas Semiconductor Corp. worked out a communication bus system for simple sensors and other equipments called 1-wire protocol. This protocol provides low-speed data exchange, signaling and power over single signal wire. It is possible to connect up to 75 devices to one bus, forming MicroLan networks. MicroLan networks have one master unit, what controls network' | ||
| 1-wire communication is mostly used for communicating between different sensors and memory units. Bus data transfer rate is approximately 16.3 kbit/s. Communication is started by a master with the " | 1-wire communication is mostly used for communicating between different sensors and memory units. Bus data transfer rate is approximately 16.3 kbit/s. Communication is started by a master with the " | ||
| - | To find all devices, master send an enumeration command, and an address. For each bit master listens the answer. If slave device has all right address bits it returns a 0. Master uses this simple behavior to search for valid sequences of address bits. An enumeration of 10 or 15 devices finishes very quickly. | + | [{{ : |
| - | {{:et: | + | [{{ :en: |
| - | {{: | + | To find all devices, master send an enumeration command, and an address. For each bit master listens the answer. If slave device has all right address bits it returns |
| - | A read-time is initiated by master device pulling the 1-wire bus low for a | + | A read-time is initiated by master device pulling the 1-wire bus low for a minimum of 1 µs and then releasing the bus. Slave device transmits a 1 by leaving the bus high and transmits a 0 by pulling the bus low. |
| - | minimum of 1 µs and then releasing the bus. Slave device transmits a 1 by leaving the bus high | + | |
| - | and transmits a 0 by pulling the bus low. | + | |
| When transmitting a 0, slave device releases the bus by the end of the time, and the bus will be pulled back to its high idle state by pull-up resistor. Output data from the slave is valid for 15 µs after the falling edge which initiated read-time. | When transmitting a 0, slave device releases the bus by the end of the time, and the bus will be pulled back to its high idle state by pull-up resistor. Output data from the slave is valid for 15 µs after the falling edge which initiated read-time. | ||
| Line 25: | Line 24: | ||
| ===== Practice ===== | ===== Practice ===== | ||
| - | The DS18S20 digital thermometer provides 9–bit centigrade temperature measurements and has an | + | The DS18S20 digital thermometer provides 9–bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. A digital thermometer DS18S20 with a 1-wire communication protocol can be connected with Robotic HomeLab Sensor module external sensor connectors. |
| - | alarm function with nonvolatile user-programmable upper and lower trigger points. A digital thermometer DS18S20 with a 1-wire communication protocol can be connected with Robotic HomeLab Sensor module external sensor connectors. | + | |
| Sensors' | Sensors' | ||
| Line 45: | Line 43: | ||
| Example code enabling to read the temperature with 1-wire protocol is shown below. It is important to include | Example code enabling to read the temperature with 1-wire protocol is shown below. It is important to include | ||
| - | ~~PB~~ | + | < |
| <code c> | <code c> | ||
| Line 51: | Line 49: | ||
| #include < | #include < | ||
| #include < | #include < | ||
| - | |||
| - | |||
| #include " | #include " | ||
| #include " | #include " | ||
| - | |||
| #include < | #include < | ||
| #include < | #include < | ||
| #include < | #include < | ||
| - | // | ||
| // Sensor queue number and sensor' | // Sensor queue number and sensor' | ||
| - | // | ||
| extern uint8_t gSensorIDs[MAXSENSORS][OW_ROMCODE_SIZE]; | extern uint8_t gSensorIDs[MAXSENSORS][OW_ROMCODE_SIZE]; | ||
| + | // Main program | ||
| int main( void ) | int main( void ) | ||
| { | { | ||
| Line 86: | Line 80: | ||
| // Multiplexer' | // Multiplexer' | ||
| - | // to connect external sensor with the controller . | + | // to connect external sensor with the controller. |
| pin_setup_output(multiplexer_pin); | pin_setup_output(multiplexer_pin); | ||
| pin_set(multiplexer_pin); | pin_set(multiplexer_pin); | ||
| Line 98: | Line 92: | ||
| while(1) | while(1) | ||
| - | { | + | { |
| error = 0; | error = 0; | ||
| Line 112: | Line 105: | ||
| { | { | ||
| // Taking the measurements. In case of error, the error flag is set. | // Taking the measurements. In case of error, the error flag is set. | ||
| - | if ( DS18X20_start_meas( DS18X20_POWER_PARASITE, | + | if (DS18X20_start_meas(DS18X20_POWER_PARASITE,& |
| { | { | ||
| sw_delay_ms( 750 ); | sw_delay_ms( 750 ); | ||
| - | // Measurements are saved in decicelsius. In case of error, the error flag is set. | + | // Measurements are saved in decicelsius. In case of error, |
| - | if ( DS18X20_read_decicelsius( & | + | // the error flag is set. |
| + | if (DS18X20_read_decicelsius(& | ||
| { | { | ||
| - | |||
| // Displaying the word " | // Displaying the word " | ||
| lcd_gfx_goto_char_xy(2, | lcd_gfx_goto_char_xy(2, | ||
| Line 127: | Line 120: | ||
| lcd_gfx_goto_char_xy(13, | lcd_gfx_goto_char_xy(13, | ||
| lcd_gfx_write_string(" | lcd_gfx_write_string(" | ||
| - | + | ||
| // Making the readings to strings and adding +/-. | // Making the readings to strings and adding +/-. | ||
| DS18X20_format_from_decicelsius( decicelsius, | DS18X20_format_from_decicelsius( decicelsius, | ||
| - | // If is needed maximum accuracy use this function: | ||
| - | // DS18X20_format_from_maxres( tval, s, 10 ); | ||
| - | |||
| // Displaying the temprerature | // Displaying the temprerature | ||
| lcd_gfx_goto_char_xy(7, | lcd_gfx_goto_char_xy(7, | ||
| lcd_gfx_write_string(s); | lcd_gfx_write_string(s); | ||
| - | + | ||
| - | // Displaying sensors queue number. Firstly it's converted to a string. | + | // Displaying sensors queue number. |
| + | // Firstly it's converted to a string. | ||
| lcd_gfx_goto_char_xy(0, | lcd_gfx_goto_char_xy(0, | ||
| sprintf(sensor_nr, | sprintf(sensor_nr, | ||
| Line 148: | Line 139: | ||
| error++; | error++; | ||
| } | } | ||
| - | |||
| } | } | ||
| else | else | ||
| { | { | ||
| - | // Taking the measurements failed, maybe in data bus has a short circuit | ||
| error++; | error++; | ||
| } | } | ||
| - | } | + | } |
| - | + | ||
| - | + | ||
| // Displaying the error messege. | // Displaying the error messege. | ||
| if ( error ) | if ( error ) | ||
| Line 170: | Line 157: | ||
| lcd_gfx_write_string(" | lcd_gfx_write_string(" | ||
| } | } | ||
| - | |||
| sw_delay_ms(500); | sw_delay_ms(500); | ||
| } | } | ||
| } | } | ||
| - | |||
| </ | </ | ||
