Designing A Calibrator using 16x2 LCD

hello,

i building universal calibrator using nano/uno capable of delivering millivolts, milliamps , rtd resistance. able sink it. sources given external circuit have built.

the display using 16x2 lcd. have interfaced external adc mcp3421 able 16 uv step accurate reading. else works fine now. bit of fine tuning left.

the problems facing.

1. displaying millivolts in format. eg. 100.000 mv. if goes 2 digits, becomes 99.0000 mv. how set 3 decimals only. have stated :

code: [select]

lcd.print(vin,3);

when start, 0.000 , goes till 250.000 max range. while reducing, digits reduced, decimal place increased digit. eg. while reducing 250.000 0, final value 0.00000, should 0.000. returns normal after reset arduino. how define 3 decimal places only?

2. want add rtd lookup table in program , if possible thermocouple also. how should go that? after convert resistance equivalent voltage, should take reference adc value , display temperature according table.

your comments , suggestions valuable me.

thank you

when print lcd not automatically clear there.  so, when print 250.000 there 0 in seventh position.  when subsequently print 99.000 there still 0 in seventh position on screen.  round either print 7 spaces number before repositioning cursor , printing number or print spaces after number remove digits previous number printed.

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