aprilwulan
Newbie level 1
Hi..
This is what I have this far,
I want to connect FPGA Spartan 3E and MQ-7 CO gas sensor. Firstly, I know that this sensor is analog device. So that I have to convert the signal. I'm intend to use Analog Capture Circuit from Spartan 3E board. MQ-7 need 2 kind of voltage: 5V and 1.4V. From the Spartan 3E datasheet, I know that I have to look for the gain first (for the pre-amp).
I use this formula to calculate it >> (ADC input range) / (peak-to-peak MQ-7 voltage)
For 5V,
2.5 / ((5* 2^0.5) * 2) = 0.12
To avoid clipping, the gain should not exceed 0.12. So, (according to Table 10-2) the gain is 0
For 1.4V,
2.5 / ((1.4* 2^0.5) * 2) = 0.63
To avoid clipping, the gain is 0
What should I do? I personally think that they should be different. Is this okay or not? Or I have totally wrong understanding about this?
Thank you very much for your explanation...
This is what I have this far,
I want to connect FPGA Spartan 3E and MQ-7 CO gas sensor. Firstly, I know that this sensor is analog device. So that I have to convert the signal. I'm intend to use Analog Capture Circuit from Spartan 3E board. MQ-7 need 2 kind of voltage: 5V and 1.4V. From the Spartan 3E datasheet, I know that I have to look for the gain first (for the pre-amp).
I use this formula to calculate it >> (ADC input range) / (peak-to-peak MQ-7 voltage)
For 5V,
2.5 / ((5* 2^0.5) * 2) = 0.12
To avoid clipping, the gain should not exceed 0.12. So, (according to Table 10-2) the gain is 0
For 1.4V,
2.5 / ((1.4* 2^0.5) * 2) = 0.63
To avoid clipping, the gain is 0
What should I do? I personally think that they should be different. Is this okay or not? Or I have totally wrong understanding about this?
Thank you very much for your explanation...
