Interafacing data converter with fixed point model

I have a fixed point model with inputs in the range -0.5 to +0.5 and datatype-fixdt(1,32,31). It simulates well as expected.

Next, I need to interface with simulink data converter block and check the response from this model. I have set the voltage range as -10V to +10V and output data type as int 16. Then I used the convert datatype model to perform the translation of ADC outputs(int16) to fixdt(1,32,31). But I get the outputs from the model as zero. Could anybody guide me in this regard to solve this problem?

Answer 1

[Muthukumar Ganesan]

Hi,

fixdt(1,32,31) can represent the range -1 to +1. Since initially your voltage range is -0.5 to +0.5, you get proper results. In the modified range -10 to +10, this cannot be fully represented in fixdt(1,32,31). You have to increase the word length fixdt(1,36,31) or decrease fraction length fixdt(1,32,27).

Hope this helps.

Thanks

[Gary]

Hi

I have connected a source which varies from -0.5V to +0.5V to ADC simulink module. The output of which is connected to my model. The ADC outputs a int16 data and all that I have to do is to interface to a already converted fixed type model whose inputs are defined as fixdt(1,32,31).