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Honored Contributor
Honored ContributorPrinting 32bit signed 2s complement data via JTAG UART
I'm trying to print out samples generated by the WM8731 audio codec on the DE2 board via the JTAG UART in a Nios II system. The samples are deserialized in Verilog HDL, squared (this is needed for a...
Altera_ForumHonored Contributor
Honored ContributorI've been sending in a square wave and sine wave of varying amplitude (0 V up to 6.2 V). Clipping doesn't occur until 6.2 V so this must be the max input range (I appear to have been making a stupid mistake and taking the chip supply voltage as the input signal voltage). Multiplying the samples by Q = (6.2 - 0V)/2^16 = 0.0946 now gives me the proper results (I hope!).
2 Vpp, 1Khz, square wave input signal gives me ADC samples of approximately +/- 1000, which I assume is +/- 1V. Varying the input amplitude to 3 Vpp gives ADC samples of +/- 1500 which also appears correct. However, a secondary problem has shown up: DC input signals don't work. The ADC samples remain approximately 0 even with a varying DC input. I configured the WM8731 codec to disable the ADC high pass filter but it still appears to be removing the DC signal... --- Quote Start --- From the datasheet: When the high-pass filter is enabled the dc offset is continuously calculated and subtracted from the input signal. By setting HPOR the last calculated dc offset value is stored when the high-pass filter is disable and will continue to be subtracted from the input signal --- Quote End ---
