pcm1774 problem

ElTono

Other Parts Discussed in Thread: PCM1774

Hello,

I'am trying to connect a pcm1774 to a stellaris mcu over spi. The mode pin is connected directly to ground. CS, MOSI, SCK are connected to the MCU. All power supplies (VIO,VDD,VCC,VPA) are connected to +3,3V. The other pins pins 9 (SCKI), 10 (BCK), 11 (LRCK) are not connected until know. I'm trying to power up the VCOM over the register setting: 0x4A01, but I still can not measure voltage on pin. So I think the dac don't unterstand the message, but I don't know where I'm wrong. I'm using SPI Mode 0(SPO=0 and SPH=0).

Can anyone help?

Attached a measurement of the SPI Interface:

over 13 years ago

0 Patrick Galvin over 13 years ago

TI__Genius 16270 points

EITono,

Can you verify all timing requirements are met per page 20 of the PCM1774 d/s? It looks like the clock may have a pulse cycle that is too quick (<500nS)?

0 ElTono over 13 years ago in reply to Patrick Galvin

Prodigy 70 points

Hello,

you can see in the following picture that the pulse cycle is with 2.5 uS much bigger than the requirements. Also with the other timing requirements I couldn't find any violation. Did the DAC need a Clock Source to power up the Vcom voltage?

0 ElTono over 13 years ago in reply to ElTono

Prodigy 70 points

so now I found the problem: I didn't power up the analog bias circuit(register 0x49). Reading the whole datasheet often helps ;) sorry for all efforts.

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pcm1774 problem