gres
Full Member level 4
I made this project just for curious, what can I do with Attiny13? Answer is “a lot”. In this case, it can measure voltage, current, temperature, calculate data, and show results in simple way at alphanumerical display ( type HD44780). That’s not all, software have been created in bascome. Althought a few of untypical solutions, system can work as a voltage meter for amplifier, in situations when you need greate exactitude. Board dimensions are 35x16mm. I recommended it for those who put such a big microcontrollers as atmega8 to RGB lamps. Range of measuring voltage is 0-99V witch resolutions 0,1V, based on R/R divider. Range of measuring current 0-9,99A with resolution 10mA, based on R ,1 ohm shunt. Reference voltage is a inside voltage 1,1V with 10A, voltage lost is 1V, but with high resolution at all range and you don’t need executive amplifier ( so you don’t need to make negative power voltage). Temperature can be tested between 0-99*C with resolution 0,1*C – measuring thanks to LM35 analogue sensor.You must chose Voltage devider R/R and shunt to avoid overloading voltage more than 1,1V.
Disadvantages:
First resistor of divider is constant and should be 100ohm. Here’s problem of using the same pins for LCD and ADC. LCD lines at input needs 80uA to get them to GND you need work with inside puupup. Divider’s resistor 100ohm can’t get this line as we need, and there were be 7mV difference to GDN – and converter will read this result (7/1023). We can’t use resistor with bigger resistance – port will be overload while sending data to LCD- easiest way is to cancel those 7mV at software. Results won’t be perfectly linearly especially in 0-5 V range. Second problem is with current measuring. Without executive amplifier we can’t get good regulation – current can be set only “down”
More information at https://www.elektroda.pl/rtvforum/topic1570260.html