ADS7953: ADS7953 SPI Auto-1 mode Configure

Yangbo

Part Number: ADS7953

Hi Team,

My customer is using ADS7953 in their design. And they want to configure it as Auto-1 mode using SPI. Can you provide some code example?

Regards!
Yangbo

over 6 years ago

0 Sandeep Kasargod over 6 years ago

TI__Expert 4405 points

Yangbo,

I am sorry that I do not have a ready code to share with you, but this device is fairly easy to configure.

Fig 52 of the ADS7953 datasheet describes the steps involved in programming the device for Auto-1 Channel-sequencing mode.

Let us assume that the customer is interested in configuring the device to capture data from Channels 1,3 and 5, in Range 2 and with GPIO0 as output high

Here is the sequence of commands to send over the SDO to configure the device:

>> wr 0x4200 // Device resets all registers in the next CS frame to the reset states (it also resets itself).

>> wr 0x4001 // Configure GPIO0 as a general purpose output

>> wr 0x8000 // Program Register for Auto-1 Frame 1

>> wr 0x002A // Program Register for Auto-1 Frame 2, to select channels Ch1,Ch3 and Ch5

>> wr 0x2C40 // Enable Auto-1 Mode, counter set to lower programmed channel (Ch1), Select Range 2 operation

>> wr 0x2841 // Stay in Auto-1 Mode, enable increment counter, Range 2 operation and GPIO set as output high

The device is now configured and these setting can be retained by driving SDI low. The channel selection will cycle through the 3 channels with each subsequent frame.

Hope this helps. Do let me know if you need any clarifications on this.

Thanks.

Regards,

Sandeep

0 Tobby Guo over 6 years ago in reply to Sandeep Kasargod

Intellectual 770 points

Thanks for your replay.

I follow your instruction give the below instruction to configure the divice

//we dont use GPIO, so omit the instruction of 0x4200 and 0x4001

>> wr 0x8000 // Program Register for Auto-1 Frame 1

>> wr 0xFFFF // Program Register for Auto-1 Frame 2, to select all 16 channles

>> wr 0x2C00 // Enable Auto-1 Mode, counter set to lower programmed channel (Ch1)

>> wr 0x2841 // Stay in Auto-1 Mode, enable increment counter, Range 2 operation and GPIO set as output high

>> wr 0x000 all

give the instructions above it only give the result of CH15, oscilloscope display

0 Tobby Guo over 6 years ago in reply to Sandeep Kasargod

Intellectual 770 points

CH1:SDI CH2:SDO CH3:CLK CH4:/cs

0 Tobby Guo over 6 years ago in reply to Tobby Guo

Intellectual 770 points

anothe question: In Figure 51, every frame SDI : Programming for ‘frame n+1’ DI15..12 = 0010, is this a necessary configer ? thank you

0 Yangbo over 6 years ago in reply to Sandeep Kasargod

TI__Intellectual 1690 points

As is shown in Table 7 in the datasheet, to stay in Auto-1 mode, write 0x0000 instead of 0x2841.

And what do you mean by driving SDI low?

Thanks a lot!

Regards!

Yangbo

0 Sandeep Kasargod over 6 years ago in reply to Yangbo

TI__Expert 4405 points

Yangbo,

You could stay in a given mode by either reprogramming the bits for that mode in every frame or by writing 0x0000 as mentioned in Table 7. By "driving SDI low" I meant writing 0x0000 for no change, as you have correctly mentioned.

Regards,

Sandeep

0 Sandeep Kasargod over 6 years ago in reply to Tobby Guo

TI__Expert 4405 points

Tobby,

Your register write sequence is correct.

I would have made two small modifications and written the following:

>> wr 0x4200 >> wr 0x8000 >> wr 0xFFFF >> wr 0x2C00 >> wr 0x2840 >> wr 0x000 >> wr 0x000 >>..

The 0x4200 ensure that all the device registers are reset after power-up and 0x2840 since you do not want to use the GPIOs.

Please try this sequence. If this does not work we will have to look at the circuit design and timing more closely.

1. Since you are writing 0x0000, the timing of SDI with respect to the SCLK is not clear in your screen capture. Could you please share a screenshot when writing 0x4200?

2. Could you share a circuit schematics for the section of the design related to the ADS7953

Thanks.

Regards,
Sandeep