problem with the continous mode of AD7738

Hi Chris,

1.       “When reading the status register and data register Im seeing 4 bytes written to the part on the DIN line”

My answer:

I cannot use just one byte. The first byte is for the communication register to point to the data register. Then the other 3 bytes for reading the status and data register  follow. These 4 bytes are sent after the ready bit goes low.

2.     “When using the part in continuous read(continuous conversion) mode the DIN pin must be kept low”

My answer:

When I send the 3 read bytes I keep DIN low.

Because the detail of the DIN line is not clear enough in my previous e-mail I took additional pictures which I’m sending to you as attachments to this e-mail. Basically what happens is :

Send 3 bytes to initialize the continuous mode. These 3 bytes are: 38, 2C and 48. Then after the ready pin indicates that the first conversion is completed (the ready pin goes low) send 3 bytes zero (DIN is low) to read the

Status register (one byte) and the data register (2 bytes). At the same time the DIN is kept low as prescribed in the data sheet while reading these 3 bytes. Unfortunately the chip doesn’t respond.

This is exactly what the data sheet asks to be done –attached is the corresponding page of the data sheet. The only difference between the scope picture and the attached timing picture from the data sheet

is that the ready pin never goes high after I read the status register because the chip fails for some reason.

Take a look at the picture and if you find anything wrong with this picture let me know.

Again many thanks for your attention and trying to help me!!

BR,

Peter

Hi Chris,

1.       “When reading the status register and data register Im seeing 4 bytes written to the part on the DIN line”

My answer:

I cannot use just one byte. The first byte is for the communication register to point to the data register. Then the other 3 bytes for reading the status and data register  follow. These 4 bytes are sent after the ready bit goes low.

2.     “When using the part in continuous read(continuous conversion) mode the DIN pin must be kept low”

My answer:

When I send the 3 read bytes I keep DIN low.

Because the detail of the DIN line is not clear enough in my previous e-mail I took additional pictures which I’m sending to you as attachments to this e-mail. Basically what happens is :

Send 3 bytes to initialize the continuous mode. These 3 bytes are: 38, 2C and 48. Then after the ready pin indicates that the first conversion is completed (the ready pin goes low) send 3 bytes zero (DIN is low) to read the

Status register (one byte) and the data register (2 bytes). At the same time the DIN is kept low as prescribed in the data sheet while reading these 3 bytes. Unfortunately the chip doesn’t respond.

This is exactly what the data sheet asks to be done –attached is the corresponding page of the data sheet. The only difference between the scope picture and the attached timing picture from the data sheet

is that the ready pin never goes high after I read the status register because the chip fails for some reason.

Take a look at the picture and if you find anything wrong with this picture let me know.

Again many thanks for your attention and trying to help me!!

BR,

Peter