ADS1294 OUTPUT ALWAYS STURATED

Nestor Adrian

Other Parts Discussed in Thread: ADS1198, ADS1294

well I designed a board using the diagrams in the datasheet, it is feed with +-1.8v and 3.3v, i have followed the steps for initializing described in the datasheet and after the status header i get only 0x800000 or 7FFFFF, both ads1294 and ads1198 had the same behavor, what can be?

this is the diagram.

over 9 years ago

0 Brian Pisani over 9 years ago

TI__Mastermind 38745 points

Hello Nestor,

Please report your register settings.

Regards,
Brian

0 Nestor Adrian over 9 years ago in reply to Brian Pisani

Prodigy 50 points

thanks for the response, I write sequentially the next data trying to read the test signal

CONFIG1 0x06
CONFIG2 0x10
CONFIG3 0x80
LOFF 0x00
CH1SET 0x05
CH2SET 0x05
CH3SET 0x05
CH4SET 0x05

0 Brian Pisani over 9 years ago in reply to Nestor Adrian

TI__Mastermind 38745 points

Hey Nestor,

Have you been able to read those register values back successfully?

Please confirm that pins 33, 49, and 51 are tied to the board ground. On the schematic it shows they are shorted together but there is no ground symbol attached to them.

Regards,
Brian Pisani

0 Nestor Adrian over 9 years ago in reply to Brian Pisani

Prodigy 50 points

thanks for the response and sorry for the delay, i have already solved this problem lowering the spi clock speed from 5 to aprox 3.5 MHz. unfortunatly the mesurements are most noise, at first i was able to obtain some signals , and i was able to see the calibration signal, now is only noise, any idea why?,and yes, in the digram its not seen but all those pins are tied to gnd

0 Brian Pisani over 9 years ago in reply to Nestor Adrian

TI__Mastermind 38745 points

Nestor,

Are you able to read back the registers? If so, please send me the values you read.

Brian

0 Nestor Adrian over 9 years ago in reply to Brian Pisani

Prodigy 50 points

ok, this is what I obtained

register 0x00 - 0x90
0x01 - 0x15
0x02 - 0x10
0x03 - 0xC0
0x04 - 0x00
0x05 - 0x20
0x06 - 0x20
0x07 - 0x20
0x08 - 0x20
the rest are zeros

0 Brian Pisani over 9 years ago in reply to Nestor Adrian

TI__Mastermind 38745 points

Hey Nestor,

To measure the test signal, bits [2:0] of the CHnSET registers must be set to 101. Try changing them and tell me if the result improves.

Brian

0 Nestor Adrian over 9 years ago in reply to Brian Pisani

Prodigy 50 points

yes I know, that are the values i programed for some test, all are in normal electrode mode and a gain of 2, but it reads only noise, the chip never worked properly, I suppose i should try with other component, thanks anyway

0 Brian Pisani over 9 years ago in reply to Nestor Adrian

TI__Mastermind 38745 points

Nestor,

What is the signal source you are attempting to measure? You could rule out the ADS1294 as the source of the issue by inputting a known good signal and reading it back.

Brian

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ADS1294 OUTPUT ALWAYS STURATED