TLV1570: TLV5608 DAC

Hi Stan, 

Yes, FS (frame sync) is equivalent to CS (chip select). It should be pulled low before transmitting to the DAC.

Can you share an oscilloscope screenshot of the full write sequence so I can check your timings. Please include, SCLK, FS, and DIN. You can try writing 0x0AAA so it is clear to see DIN changing on the oscilloscope. 

Please also share a schematic. What are AVDD and DVDD supplied with? 

Best,

Katlynne Jones 

HI Kat pls see screenshot attached for 0AAA and schemetic...

Hi Katlynne pls see below the full write sequence 0ffc 1ffc 2ffc 3ffc for chA B C D ... pls advise...

Hi Stan, 

The timing here looks ok and it looks like you are using a valid SPI mode. To double check, are you sharing a ground between the STM device and the TLV? It is not shown in your schematic. 

I assume this is a mistake in the way you have drawn your schematic, but you have MISO pin of the STM connected to the FS pin of the TLV. FS of the STM should be connected to FS of the TLV, and MISO of the STM should be connected to DOUT of the TLV if you would like to have SPI readback. 

The datasheet mentions to power on the AVDD supply before the DVDD supply if the supplies aren't shared. I see they are both coming from the STM device, can you verify that they are coming up at the same time, or that AVDD is coming up before DVDD? 

Best,

Katlynne Jones

Hi Katlynee, 

1. yes all GND shared between DAC and STM.

2. You are right, typo error, DAC FS is connected to STM FS, MISO not connected since i not reading back anything.

3. AVDD and DVDD is shared and coming up same time.  When try powering AVDD first before DVDD, same result as powering both at same time. 

i also observe OutA B C D Is pulsating between 3~3.6v when Vref is 5v and command line input is 0ffc, 1ffc, 2ffc, 3ffc...OutE, F G H is outputing same 3~3.6v when not even programmed the command.. pls advise,,

Hi Stan, 

Can you connect the /PRE pin to DVDD? I don't expect that that is causing the behavior you mentioned, but inputs should not be left floating. 

This does not sound like normal behavior for the device. Is it possible that the device could have been damaged while connecting it to the STM? Based on your previous post it looks like the device had different behavior initially. Given that you have not changed anything with the codes you were writing between now and then I suspect that the device has been damaged. 

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/1278422/tlv1570-mcu-sample-code-for-spi-interface-to-tlv5608-tlv1570-adc-dac#pifragment-323207=1

Best,

Katlynne Jones   

Hi Kathlynne

DAC is working fine now, thanks. I now go back to TLV1570 ADC which is intermittenly working. I use the same SPI write and SPI read from DAC code to sampled ch0 only. i use the example4 Auto Scan Mode on page7 TLV1570 datasheet, and i enclose the short C code below, and i "AND" the received SDout with 3FF hex to obtain the LSB 10 bit from page27. Pls advise...

main()

{

....

spi_write(0x480);

while(1)

{

   spi_write(0x0480);

   spi_read(0x0400)

....;

}

e2e.ti.com/.../tlv1570-mcu-sample-code-for-spi-interface-to-tlv5608-tlv1570-adc-dac

Please remove spi_write(0x0480); from your while (1) loop.  The part will sequence through all 8 channels.  If you only want to sample CH0, do not put the part into auto sequence mode.

HI Tom still the same no output reading.. is the masking of 3FF enough to obtain the LSB 10 bit for SDout?

Stan,

Masking conversion results with 0x3FF are secondary actions.  Please continue to provide screen shots of the SPI control lines to show us exactly what you are doing.  The /CS, SCLK, SDI and SDO are what we need to see.

same waveform i update before in the previous thread 

e2e.ti.com/.../tlv1570-mcu-sample-code-for-spi-interface-to-tlv5608-tlv1570-adc-dac

Hi Tom there u go

Hi Katlynne could you help to advise..

Your SCLK is not reaching proper VIL levels.  Please fix that!

resend...  

i also observed SDout show random voltage even when no input was supplied to CH0. Hi Katlynne could you pls help to advise..

Hi Stan,

Without a proper clock, you can get strange outputs.  You need to fix that on your processor side of things.

Hi Tom,  better waveform ..

Slightly better - you have a lot of over and under shoot on the SCLK and there is ringing as well.  Do you have a proper PCB or are you wiring parts with a proto board?  Without clean control signals I can't do much to help.  You have had the ADC working before, so what's changed?

Hi Tom, I m implementing the ADC on breadboard, IC soldered on a TSSOP adapter PCB board... connection same as before...

I suspected as much - perhaps its time to build a proper PCB?

Hi Tom i forward a better screenshot....see enclosed.

Hi Tom, more waveform..

There is still too much noise and ringing on your SCLK.