Hello,
In the datasheet of the ADS1220 it is mentioned that to read data without interruption, it is necessary to keep DIN low while clocking out data.
To make it simple, the SPI master that I want to use can manage a read command in both ways :
first way :
CS |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
SCK |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
MOSI |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
MISO |
- |
- |
- |
- |
- |
- |
- |
- |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
second way :
CS |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
SCK |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
! |
MOSI |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
MISO |
- |
- |
- |
- |
- |
- |
- |
- |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
d |
As I did not succeed in attaching a file, I will transmit the corresponding timing diagrams in a separate e-mail.
How does the ADS1220 exactly behave when DIN is kept high ? Does the response of the ADS1220 on DOUT can meet the expected MISO signal in both cases ? For information, I already have added some glue logic to force DIN low from d23 to d00, otherwise MOSI returns high from d23.
Regards
Didier