Hi
I am new here and I have a wired problem that I need to solve.
I have a pressure and a humidity sensor that give a voltage output analogue range from 4.7V - 0V.
I am using an AT89C51 micro controller and the ADC input accepts a voltage with the a range of 2.55V - 0V (FF - 00).
When I connect the sensor's Vref pin with the ADC, the voltage at the ADC port will be the voltage of the Vref of the sensor. Now since the 89C51 accepts not more then 2.55V for conversion, I must reduce that 4.7V to 2.55V or less.
I did a voltage division to reduce the 4.7V to 2.0V but when I connect that 2V with the ADC, the ADC will give 5V wrt ground ignoring the 2V and will give wrong readings (obviously).
This is really confusing me and I cant seem to find any solution for it since I dont know what I am doing wrong.
How can I convert the 4.7V of the sensor to digital when the ADC is accepts only a max of 2.55V.
Any help would be greatly appreciated right now.
Thanks
Regards
Ed
I am new here and I have a wired problem that I need to solve.
I have a pressure and a humidity sensor that give a voltage output analogue range from 4.7V - 0V.
I am using an AT89C51 micro controller and the ADC input accepts a voltage with the a range of 2.55V - 0V (FF - 00).
When I connect the sensor's Vref pin with the ADC, the voltage at the ADC port will be the voltage of the Vref of the sensor. Now since the 89C51 accepts not more then 2.55V for conversion, I must reduce that 4.7V to 2.55V or less.
I did a voltage division to reduce the 4.7V to 2.0V but when I connect that 2V with the ADC, the ADC will give 5V wrt ground ignoring the 2V and will give wrong readings (obviously).
This is really confusing me and I cant seem to find any solution for it since I dont know what I am doing wrong.
How can I convert the 4.7V of the sensor to digital when the ADC is accepts only a max of 2.55V.
Any help would be greatly appreciated right now.
Thanks
Regards
Ed