MX022 - Dual Channel Temperature Logger

[DavidA]

Article: https://www.matrixtsl.com/resources/get ... php?id=433

Please discuss this article here!

[JohnCrow]

This article shows a simple modification to my system to allow remote monitoring

The LM35 is a very useful device, however if it is mounted any distance from the microcontroller, the voltage drop in the cables can introduce errors. 10mV/°C equates to 1mV/0.1°C.
i.e. for every mV lost gives an error of 0.1°C

The following system uses two EB006 programmers linked using the USART on Port C.
However this could easily be replaced by a full RS232 or RS 485 connection.

For the purpose of this version, I have removed the min-max functions and the USB interface.

The remote sensor can use a simpler microcontroller, and I have selected the 16F877A

Remote Board
Uses a PIC 16F877A

Port A (ADC 0) has a LM35 connected
Port B is the standard LCD E-Block
Port C has a 9 pin D-plug wired with pins 7 & 8 crossover to the second programmer, and pins 9 to 9 connected as a ground link.
The LCD shows the temperature in degrees Celsius.
The label on the LCD shows “Local Temperature”.
This is because, although this is designated the remote board, if you are looking at the display it is local to you.
The temperature is sent as a data string using the RS232 protocol.
The software is set to transmit every 5 seconds, though this can be changed if needed.
The display will also show “Tx” in the bottom right when the data is sent, for 100ms

Remote Board

Remote.jpg (170.25 KiB) Viewed 25304 times

Local Board
Uses a PIC 18F4550

Port A has the E-Block Card Reader with 2GB SD Card
Port B is my custom 4x20 LCD Board
Port C has a 9 pin D-plug wired with pins 7 & 8 crossover to the second programmer, and pins 9 to 9 connected as a ground link.
Port E (ADC 5) has a LM35 connected

This shows both Local Temperature and Remote Temperature.
Although I have retained the data logging option, the max-min and HyperTerminal connections have been removed in this version.

Local Board

Local.jpg (185.12 KiB) Viewed 25304 times

Part 3 will follow soon

[JohnCrow]

Flowcode Files

Dual Remote Rx - 18F4550.fcf

(22.69 KiB) Downloaded 1187 times

Dual Remote Tx - 16F877A.fcf

(14 KiB) Downloaded 1214 times

[medelec35]

Hi John,
Great artical!

I'm going to have a play as this is something I could use for work and home.

Thanks for sharing it.

Martin

[petesmart]

Hi John,

Great article.

I noticed your custom 4line display. Any chance you could provide detail on the hardware and also the V4 flow code component that you used to drive the display.

Many thanks

Pete

[JohnCrow]

Hi Pete

The display is from Rapid Electonics http://www.rapidonline.com

The part no. 57-0946 - data sheet is on rapids website
Not sure where you'll get one in your country, but the data sheet should point you in the right direction.

Though any display with these connections and a Hitachi HD44780 or Samsung KS0066U compatible controller chip will work.

They are wired exactly the same way as the 2x16 standard e-block. Full data for this is on the Matrix data sheet.
The board is the Matrix EB017 Patch board.
Uses the normal LCD flowcode component, just select LCD, right click on it and select 4x2


I would also recommend trying a smaller value pot, 20k was shown on the data sheet but it only operates over the top 30% or so of the travel.

[petesmart]

Many thanks John,

Appreciate the fast response...

All the best

Pete

[dan@ttl]

Hi to all,
I have tried the Remote Tx on hardware, but am getting high swing readings on the display. Increasing the delay doesn't help. The voltage on the adc seem constant eneough. I have all my power connections decoupled.