Digital thermometer using ATtiny85 a thermistor(ntc), and 4-digit 7 segment led display

Thread Starter

Chiho9

Joined Oct 18, 2020
20
Hi everyone.
As a hobbyist,I want to design a digital thermometer using an ATtiny85 controller and a thermistor.
The result will be displayed on a 4-digit seven segment display.
This is actually my first project involving a microcontroller so I need a lot of advice on what I'm about to do.
I don't really know where to start from.
The 7-segment has 12 pins and the MCU has 8.
The tutorials I went through used a max7219 to interface with the led and then the controller.
But the temp sensor in that case was a temp ic instead of a thermistor.
How do u think I should go about this
 
Last edited:

Papabravo

Joined Feb 24, 2006
16,151
Hi everyone.
As a hobbyist,I want to design a digital thermometer using an ATtiny85 controller and a thermistor.
The result will be displayed on a 4-digit seven segment display.
This is actually my first project involving a microcontroller so I need a lot of advice on what I'm about to do.
I don't really know where to start from.
The 7-segment has 12 pins and the MCU has 8.
The tutorials I went through used a shift register(max7249) to interface with the led and then the controller.
But the temp sensor in that case was a temp ic instead of a thermistor.
How do u think I should go about this
If you want a functional device, I would take the path of least resistance. If you want a challenge to demonstrate your design chops, then go for the minimalist design choices.
 

KeithWalker

Joined Jul 10, 2017
1,785
An ATtiny is not a good choice to drive a seven segment display. It does not have enough digital pins, You will need extra circuitry to convert a serial data stream into parallel data to strobe the display. There are a couple of much simpler choices you could make. Either change the display to LED or TFT LCD with a I2C interface or use a micro-c with more data pins.
 

MrChips

Joined Oct 2, 2009
23,528
Let's start with the back end, the LED display.
Post the LED part number and datasheet if you have it.
Sit down and figure out how you will map the ATtiny85 GPIO pins to the LED display.

For starters, write a simple "blinky" program that will make a single individual LED (not the 7-segment display) flash twice each second.
 

Thread Starter

Chiho9

Joined Oct 18, 2020
20
An ATtiny is not a good choice to drive a seven segment display. It does not have enough digital pins, You will need extra circuitry to convert a serial data stream into parallel data to strobe the display. There are a couple of much simpler choices you could make. Either change the display to LED or TFT LCD with a I2C interface or use a micro-c with more data pins.
OK.
If I change the display to TFT LCDi
An ATtiny is not a good choice to drive a seven segment display. It does not have enough digital pins, You will need extra circuitry to convert a serial data stream into parallel data to strobe the display. There are a couple of much simpler choices you could make. Either change the display to LED or TFT LCD with a I2C interface or use a micro-c with more data pins.
If I consider using another micro c, would PIC18f42 do the trick or do I need an atmega328 or equivalent
 

Thread Starter

Chiho9

Joined Oct 18, 2020
20
Let's start with the back end, the LED display.
Post the LED part number and datasheet if you have it.
Sit down and figure out how you will map the ATtiny85 GPIO pins to the LED display.

For starters, write a simple "blinky" program that will make a single individual LED (not the 7-segment display) flash twice each second.
Let's start with the back end, the LED display.
Post the LED part number and datasheet if you have it.
Sit down and figure out how you will map the ATtiny85 GPIO pins to the LED display.

For starters, write a simple "blinky" program that will make a single individual LED (not the 7-segment display) flash twice each second.
OK I'll try this then get back to u
 

MrChips

Joined Oct 2, 2009
23,528
ATtiny85 is on a 8-pin chip. With two pins for power and ground this leaves you with only 6 pins to work with. You can do this if the display uses a serial interface.

Otherwise there are hundreds/thousands of other viable MCUs to choose from. For a parallel interface to four 7-segment LED displays you can get away with 6-11 output pins from the MCU.

At this point it really doesn't matter which MCU you select to start on your journey. Pick an MCU and learn how to write a program to make an LED flash. You can/will always change to another MCU as the application demands.
 

KeithWalker

Joined Jul 10, 2017
1,785
OK.
If I change the display to TFT LCDi

If I consider using another micro c, would PIC18f42 do the trick or do I need an atmega328 or equivalent
if you are going to use a TFT LCD display, the ATtiny will work fine. I recommend that you check out this tutorial and try it when you get your display.

http://www.technoblogy.com/show?L6I

Adding the thermistor will only use one pin on the tiny. There are lots of tutorials on-line on how to do that once you have the display working - one step at a time for best results.
 
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