Difference between revisions of "Thermocouple"

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(See also)
(Protocol)
 
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== Overview ==
 
== Overview ==
  
The board has 7 fets that allow you to pull a pin of a load low. You would normally tie the other end of your load directly to the powersupply.  
+
The Thermocouple has a low voltage of max about 75mV. The low voltage is temperature sensitive, so that makes it possible to read the temperature with it.
  
About 1A per output should be possible. Maximum voltage is 20V. [http://www.bitwizard.nl/contact.php Contact] us if you require a larger voltage.
+
The board has 4 pins, which can be changed to input or output.
 
 
You will have to provide your own protection circuits (freewheeling diodes) if you are going to drive inductive loads (like a motor).
 
  
 
== Assembly instructions ==
 
== Assembly instructions ==
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None: the board comes fully assembled.
 
None: the board comes fully assembled.
  
== Specifications ==
 
 
The 7FETS board is capable of sinking about 1A per output. We have tested 1.25A and the FET became slightly warm, as predicted by theory.
 
 
Although the specifications for the FETs allow a larger current, it is not recommended to exceed the 1A as the contacts of the connectors are not rated for so much, also the PCB is not equipped for such large currents. But if you need to drive several loads in sequence 1A per port is comfortably possible.
 
  
The manufacturer specifies the maximum current for the case where each fet has the whole board available as a heatsink.
 
  
 
=== Possible Configurations ===
 
=== Possible Configurations ===
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=== Datasheets ===
 
=== Datasheets ===
[http://www.irf.com/product-info/datasheets/data/irfml8244pbf.pdf The FETs]
+
 
  
 
== Additional software ==
 
== Additional software ==
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For the SPI connector see: [[SPI_connector_pinout]].  
 
For the SPI connector see: [[SPI_connector_pinout]].  
  
The output connector is connected as follows:
+
Normal measurements would return a value of 0 for 0V up to 1023 for the reference value.
 +
 
 
{| border=1
 
{| border=1
! pin !! function !!
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! value !!   thermo
|-
 
| 1 || DEV POWER ||
 
|-
 
| 2 || OUT0 ||
 
|-
 
| 3 || DEV POWER ||
 
|-
 
| 4 || OUT1 ||
 
|-
 
| 5 || DEV POWER ||
 
|-
 
| 6 || OUT2 ||
 
|-
 
| 7 || DEV POWER ||
 
 
|-
 
|-
| 8 || OUT3 ||
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| 0x00    || T4
 
|-
 
|-
| 9 || DEV POWER ||  
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| 0x01    || T3
 
|-
 
|-
| 10 || OUT4 ||
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| 0x02    || T2
|-
 
| 11 || DEV POWER ||  
 
 
|-
 
|-
| 12 || OUT5 ||
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| 0x03    || T1
 
|-
 
|-
| 13 || DEV POWER ||
 
|-
 
| 14 || OUT6 ||
 
 
|}
 
|}
  
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Use a connector on 1-2 to provide a more powerful power source for the devices that the board drives.  
 
Use a connector on 1-2 to provide a more powerful power source for the devices that the board drives.  
  
 
+
More info you can read at [[analog inputs]].
  
 
=== LEDs ===
 
=== LEDs ===
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The connector SV2 allows you to connect the "power source".  
 
The connector SV2 allows you to connect the "power source".  
 
You can chose two configurations: You can use pin 1-2 as ground and power. You can connect up to 15V (*) to pin 2 referenced to GND on pin 1.
 
  
 
(*) The datasheet for the used transistors mentions "20V", but is is always prudent to keep some margin.  
 
(*) The datasheet for the used transistors mentions "20V", but is is always prudent to keep some margin.  
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If you want 5V as the power source, you could put a jumper on pin 2-3. In that case you will have to be aware that you're using the 5V power from the rest of the system. This will be limited by e.g. USB power limits, other devices on the SPI bus, cable thickness and connector capability. But for low-current 5V applications this might be useful.
 
If you want 5V as the power source, you could put a jumper on pin 2-3. In that case you will have to be aware that you're using the 5V power from the rest of the system. This will be limited by e.g. USB power limits, other devices on the SPI bus, cable thickness and connector capability. But for low-current 5V applications this might be useful.
  
== jumper settings ==
+
== Jumper settings ==
  
 
See [[solder jumpers]] on how to change the solder jumper.  
 
See [[solder jumpers]] on how to change the solder jumper.  
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By changing the solder jumper SJ1, you can make the connector nearest the board edge into the ICSP programming connector for the attiny44 on the board.
 
By changing the solder jumper SJ1, you can make the connector nearest the board edge into the ICSP programming connector for the attiny44 on the board.
  
 +
== Powering Thermocouple ==
  
== powering 7fets ==
+
Although some BitWizard boards will work with 3.3V as the power supply, the Thermocouple board needs to be supplied with 5V as this voltage is used to drive.
 
 
Although some BitWizard boards will work with 3.3V as the power supply, the 7fets board needs to be supplied with 5V as this voltage is used to drive the FETs. If you need operation at 3.3V, [http://www.bitwizard.nl/contact.php contact] us: we can find FETs to populate the boards with that work at 3.3V.
 
  
 
== Protocol ==
 
== Protocol ==
  
To make the 7FETS PCB do things, you need to send things over the SPI or I2C bus to the PCB.  
+
To make the Thermocouple be useful, you need to send things over the SPI or I2C bus to the PCB.  
  
 
The general overview of the protocol is [[General_SPI_protocol|here]].  
 
The general overview of the protocol is [[General_SPI_protocol|here]].  
  
The specific commands for the 7fets PCB are explained on the page about the spi_dio board, as the two boards share the same protocol: [[DIO_protocol]] . Where the SPI_DIO drives an output high, the 7fets board will drive the output pin LOW when the pin is driven active.  
+
The specific commands for the Thermocouple PCB are explained on the page about the spi_dio board, as the two boards share the same protocol: [[DIO_protocol]] .  
  
 
For arduino, a sample PDE is available, called ardemo_lcd.pde, also at [http://www.bitwizard.nl/software the BitWizard software download directory] .
 
For arduino, a sample PDE is available, called ardemo_lcd.pde, also at [http://www.bitwizard.nl/software the BitWizard software download directory] .
  
This is a demo to send things using SPI to the lcd board. The SPI routines there are applicable for the dio and 7fets boards as well.
+
This is a demo to send things using SPI to the lcd board. The SPI routines there are applicable for the dio and Thermocouple boards as well.
  
 
== The software ==
 
== The software ==
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== See also ==
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== Useful links ==
  
 
[http://www.bitwizard.nl/shop/expansion-boards/thermocouple The Thermocouple BitWizard shop page]<br>
 
[http://www.bitwizard.nl/shop/expansion-boards/thermocouple The Thermocouple BitWizard shop page]<br>
[[Analog inputs]]
+
[[Analog inputs]]<br>
 +
[[DIO protocol]]<br>
 +
[[SPI connector pinout]]

Latest revision as of 11:40, 10 May 2019

The Thermocouple (I2C version)

This is the documentation page for the Thermocouple, that you can buy in the BitWizard shop.

Overview

The Thermocouple has a low voltage of max about 75mV. The low voltage is temperature sensitive, so that makes it possible to read the temperature with it.

The board has 4 pins, which can be changed to input or output.

Assembly instructions

None: the board comes fully assembled.


Possible Configurations

External resources

Datasheets

Additional software

Related projects

Pinout

For the SPI connector see: SPI_connector_pinout.

Normal measurements would return a value of 0 for 0V up to 1023 for the reference value.

value thermo
0x00 T4
0x01 T3
0x02 T2
0x03 T1

The jumper has: 1: GND, 2: DEV POWER, 3: 5V (from SPI).

Put the jumper on 2-3 to use the SPI power (from the arduino? i.e. from USB? -> max at most 400 mA!)

Use a connector on 1-2 to provide a more powerful power source for the devices that the board drives.

More info you can read at analog inputs.

LEDs

Power connector

The connector SV2 allows you to connect the "power source".

(*) The datasheet for the used transistors mentions "20V", but is is always prudent to keep some margin.

If you want 5V as the power source, you could put a jumper on pin 2-3. In that case you will have to be aware that you're using the 5V power from the rest of the system. This will be limited by e.g. USB power limits, other devices on the SPI bus, cable thickness and connector capability. But for low-current 5V applications this might be useful.

Jumper settings

See solder jumpers on how to change the solder jumper.

By changing the solder jumper SJ1, you can make the connector nearest the board edge into the ICSP programming connector for the attiny44 on the board.

Powering Thermocouple

Although some BitWizard boards will work with 3.3V as the power supply, the Thermocouple board needs to be supplied with 5V as this voltage is used to drive.

Protocol

To make the Thermocouple be useful, you need to send things over the SPI or I2C bus to the PCB.

The general overview of the protocol is here.

The specific commands for the Thermocouple PCB are explained on the page about the spi_dio board, as the two boards share the same protocol: DIO_protocol .

For arduino, a sample PDE is available, called ardemo_lcd.pde, also at the BitWizard software download directory .

This is a demo to send things using SPI to the lcd board. The SPI routines there are applicable for the dio and Thermocouple boards as well.

The software

Default operation

Future hardware enhancements

Future software enhancements

Useful links

The Thermocouple BitWizard shop page
Analog inputs
DIO protocol
SPI connector pinout