jit_singh_tara
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Dear Friends ,
I designed a dc voltmeter using microcontroller renesas.
When i put 3 similar units for testing all 3 shows different values.
example : for dc 24V supply .
Meter1 : 23.5V dc.
Meter2 : 23.8 V dc.
Meter3 : 23.6 V Dc.
when i checked the Vcc it was slightly different in 3 meters as follows :
Meter1 : 4.991 V.
Meter2 : 4.975 V.
Meter3 : 4.987 V.
Now since the supply voltage is considered for reference voltage for adc conversion so obviously the difference.
How can i make the reading correct from production point of view .I dont want to use trimpot .
How to calibrate while production......?
I designed a dc voltmeter using microcontroller renesas.
When i put 3 similar units for testing all 3 shows different values.
example : for dc 24V supply .
Meter1 : 23.5V dc.
Meter2 : 23.8 V dc.
Meter3 : 23.6 V Dc.
when i checked the Vcc it was slightly different in 3 meters as follows :
Meter1 : 4.991 V.
Meter2 : 4.975 V.
Meter3 : 4.987 V.
Now since the supply voltage is considered for reference voltage for adc conversion so obviously the difference.
How can i make the reading correct from production point of view .I dont want to use trimpot .
How to calibrate while production......?