AnsweredAssumed Answered

Built-in HP filter ADSP-21469

Question asked by Senseison on Apr 5, 2011
Latest reply on May 3, 2011 by jeyanthi.jegadeesan

Hi all!

 

I have a question about the built in HP filter in ADSP-21469 with Audio EZ-Extender. I use the talkthrough example that is provided

with the software "Sharc EZ-Extender_21469 AD1939 C Sampled-Based Talkthru 192 kHz_6serialports". Now I want to activate the

built in HP filter for the ADC via the ADCCTRL0 register. For the 1939A codec on the ADSP-21469 the ConfigParam1939A looks like

this:

 

ConfigParam1939A [] = {
            (AD1939_ADDR), CLKCTRL0, DIS_ADC_DAC | INPUT256 | PLL_IN_MCLK | MCLK_OUT_OFF | PLL_PWR_DWN,
            (AD1939_ADDR), CLKCTRL1, DAC_CLK_PLL | ADC_CLK_PLL | DIS_VREF,
            (AD1939_ADDR), DACMUTE, 0xFF,
            (AD1939_ADDR), DACCTRL1, DAC_LRCLK_POL_INV | DAC_BCLK_POL_INV | DAC_CHANNELS_4 | DAC_LATCH_MID | DAC_BCLK_SLAVE | DAC_LRCLK_SLAVE,
            (AD1939_ADDR), DACCTRL2, DAC_WIDTH_24,
       (AD1939_ADDR), DACCTRL0, DAC_FMT_DUALTDM | DAC_BCLK_DLY_1 | DAC_SR_48K,
           (AD1939_ADDR), ADCCTRL0, ADC_SR_48K  |   ADC_HP_FILT_ON,                
             (AD1939_ADDR), ADCCTRL1, ADC_LATCH_MID | ADC_FMT_TDM | ADC_WIDTH_24,
            (AD1939_ADDR), ADCCTRL2, ADC_BCLK_SRC_INTERNAL | ADC_BCLK_MASTER | ADC_CHANNELS_4 | ADC_LRCLK_MASTER | ADC_LRCLK_POL_INV | ADC_BCLK_POL_INV | ADC_LRCLK_FMT_PULSE,
            (AD1939_ADDR), DACVOL_L1, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_R1, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_L2, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_R2, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_L3, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_R3, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_L4, DACVOL_MAX,
            (AD1939_ADDR), DACVOL_R4, DACVOL_MAX, 
            (AD1939_ADDR), CLKCTRL0, DIS_ADC_DAC | PLL_IN_MCLK | MCLK_OUT_OFF | INPUT256 | PLL_PWR_UP,
            (AD1939_ADDR), CLKCTRL0, ENA_ADC_DAC | PLL_IN_MCLK | MCLK_OUT_OFF | INPUT256 | PLL_PWR_UP,
            (AD1939_ADDR), DACMUTE, 0x00,
            };
where ADC_HP_FILT_ON is 0x02 and ADC_SR_48K is 0x00, so the ADCCTRL0 holds now 0x02. This is 0b00000010, which according to the
datasheet should activate the built-in HP filter. When I build this and then send an 8Hz sinewave into the ADC and measure the corresponding
signal on the output, there is still a 8Hz sinewave on my oscilloscope. Is there anything that I miss? Maybe some switch on the DSP or the
extender board that has to be activated to initialize the filter?
Thank you for the help in advance
Greetings
Chris

Outcomes