Thermometer project using Mikroe 7seg Click (2x 74HC595) and Mikroe Thermo 4 Click (LM75B)

[andeug]

Hi,


I have been trying for a few hours to build a thermometer using the Mikroe 7seg Click and the Mikroe Thermo 4 Click, both connected to an Arduino Uno, but I cannot get it to work. What I need is to display the temperature reading from an LM75B using 74HC595 shift registers.

IMG_0691.jpeg (173.94 KiB) Viewed 223 times

I want a scenario where the first digit is omitted when the value is between 01 and 09 degrees Celsius, so the display shows only the 2nd digit.
Also, if the value exceeds 10 degrees Celsius, both digits will be displayed.

I have prepared the LUT for my display. Can someone please help me with the code?


Thank you,
Andreas

[mnfisher]

I'm not at a computer right now but you need t do something like:

if temp < 10
DisplaySegments(0, 0) // Clear first digit
else
DisplaySegments(0, temp / 10) // Display the '10s' digit
then
DisplaySegments(1, temp % 10) // Display the units

I've ignored several important details (for example you'll need to convert the temperature in degrees to the required digit / segments value. If you are handling the multiplexing in code (rather than the component) - you'll need to 'alternate' between showing digit 0/digit 1

I'll try and give more detail if you need later....

Martin

[andeug]

I can't make it to work. Enclosed is what I have tried...

Thermometer with 2x 7segs and 2x 74HC595.fcfx

(16.84 KiB) Downloaded 6 times

Also, regarding LM75B, with A0 = A1 = A2 = GND, the LM75A uses the default I²C address 0x48.

I have enclosed the schematic of Mikroe Thermo 4 Click.

Thermo 4 Click schematic.pdf

(224.13 KiB) Downloaded 8 times

[mnfisher]

Some suggestions:

1) You read the temperature as a float and then do if temp = 0 - it would be easier to do ReadInt (the temp will probably rarely exactly equal 1 (1.0000) etc)
2) Open a COM (UART) port and output data (temperature) to check it is being read correctly.
3) You are using WriteSegments - use WriteDigit (and change this when everything is working if needed)
4) You should just do Initialise once (not in the loop)

It might help?

Martin

[Bijumon]

Hi,

Try this attached example, I hope it works for you!

While debugging the I2C data, I noticed that the Flowcode LM75B component uses a hardcoded I2C address 0x92 for Writing and 0x93 for Reading.
In the picture of your hardware, your LM75B address jumpers are currently set for 0x90 and 0x91 (all pins grounded).
To fix it you just need to change your hardware address jumpers to match the software.
A0 > Move this jumper to VCC.
A1 & A2 > Keep these connected to GND.
This will change the address to match the 0x92/0x93

Best regards.

[andeug]

Hi Bijumon,


I have followed your instructions and moved the A0 jumper to VCC. The new setup works!
Now I have a different problem. In my earlier interactions with the Mikroe 7seg Click display, I found that:

DP is on Q0 of 74HC595
B is on Q1 of 74HC595
A is on Q2 of 74HC595
... and the other segments, of course, are not in the right order, as mapped by the component itself:

7-seg Click schematic.pdf

(113.59 KiB) Downloaded 6 times

Also, I could not find the original component for download (error 404):

https://flowcode.co.uk/wiki/index.php?t ... _(Segment)

What I was using before was ShowSegments, to which I was sending the following values to obtain the numbers from the right side:

Address ShowSegment
0x7E => 0
0x0A => 1
0xB6 => 2
0x9E => 3
0xCA => 4
0xDC => 5
0xFC => 6
0x4E => 7
0xFE => 8
0xDE => 9

So the simulation with ShowDigit was working correctly, but my display shows something else now due to the reversed pins:

IMG_0693.jpeg (160.74 KiB) Viewed 87 times

Do you know how to fix this? I wouldn't alter the original component, but maybe add code to change the LUT.


Andreas

[Bijumon]

Hi,

Create a data array with the size of 10 (e.g., 7Seg_data[10]).

Initial with the correct byte values to display numbers from 0 to 9 based on your display type.

Then call ShowSegments as follow
Digit - 0
Segments - 7Seg_data[Digit_Tens]
Digit - 1
Segments - 7Seg_data[Digit_Units]

[andeug]

Thank you, now it works as expected!
I am posting the code for my little project, enclosed, so that everyone can see it.

Thermometer with 2x 7segs and 2x 74HC595.fcfx

(11.82 KiB) Downloaded 4 times

Is it okay for the LM75B I2C's address to be hardcoded, or should this component be changed to allow a custom address? Luckily, in my case, I had a jumper/0R resistor which I could change, but in fixed/final designs it's hard to make changes...