ADS1298 Channel Data Reading

Hi Ekrem!

What hardware are you using with the ADS1298?  Is this your own design or are you using our ADS1298ECG-FE board?  Can you provide the configuration register contents to us?

Hi Tom,

Thank you for your fast response. I use ADS1298ECG-FE Board with EVM5515. I use the same configuration came with ADS1298ECG_FE and below is the content.

Uint32 ADS1298RegVal[28] = {

//Write register opcode1
0x0041,
//Write register opcode2
0x0018,
//CONFIG1 0x0001
0x0082,
//CONFIG2
0x0010,
//CONFIG3
0x00DC,
//LOFF
0x0003,
//CH1SET (PGA gain = 6)
0x0000,
//CH2SET (PGA gain = 6)
0x0000,
//CH3SET (PGA gain = 6)
0x0000,
//CH4SET (PGA gain = 6)
0x0000,
//CH5SET (PGA gain = 6)
0x0000,
//CH6SET (PGA gain = 6)
0x0000,
//CH7SET (PGA gain = 6)
0x0000,
//CH8SET (PGA gain = 6)
0x0000,
//RLDSENSP (default)
0x0006,
//RLDSENSM (default)
0x0002,
//LOFF_SENSP
0x00FF,
//LOFF_SENSM
0x0002,
//LOFF_FLIP (default)
0x0000,
//LOFF_STATP (Read only)
0x0000,
//LOFF_STATM (Read only)
0x0003,
//GPIO
0x0000,
//PACE (default)
0x0000,
//RESP (default)
0x0000,
//CONFIG4
0x0002,
//WCT1
0x000A,
//WCT2
0x00E3,

};

Tom, could you please respond to this topic until I figure out the problem with your help? Because after few messages I do not take any response from TI guys which puts my problems unsolved and prevents me to proceed. If you like I can also send my code via e-mail.

Regards.

Ekrem -

Looking at the first couple lines of your attached info, can you verify the register write opcodes?   We are not sure what the difference is between your two different opcode commands.

From d/s, page 40...the register write command needs 2 bytes, appears you only have one.  The opcode contains both the starting register location and number of registers to write - 1, so make sure this data is included in the correct form in your code.

For example - if you wanted to write to write to CONFIG1only, you would need to send the opcode 0x4100 and then your CONFIG1 data.  For writing CONFIG1 and CONFIG2, 0x4101, and then CONFIG1 data, followed by CONFIG2 data.

Hi Greg,

Below buffer values are send respectively which means the configuration registers will be written starting from address of 0x01 and 24 registers (0x0018) will be written. This means that I already have two byte opcode. 

 //Write register opcode1

0x0041,
//Write register opcode2
0x0018,

By the way, I have already read the values in configuration registers and below is my reading:

Therefore, there is another problem which I cannot figure out for about two weeks now :(

Regards.

I also tried to skip to configure ADS1298 and just read the data and the result is the same.

Ekrem -

You said you are writing 24 register above (0x18)...you meant to say 25 correct? (I just want to make sure you have enough data, the opcode is number of registers -1).  I am pretty sure this is not the problem, but just wanted to check.

In the original post, the array that you included is your data you are writing?  If so, it appears there may be a write issue (timing perhaps) since the above post containing the register read back doesn't appear to match you write array (after RLD_SENSP (0x0D)).  You may want to make sure that all the timing and frequencies are what you think they should be; it could be the first bunch of register writes OK, but by the time you get to RLD_SENSN that you get out of sync on the write operation.  You could send us some of your SPI timing so that we can note anything that may be off.

Greg Hupp said:

You said you are writing 24 register above (0x18)...you meant to say 25 correct? (I just want to make sure you have enough data, the opcode is number of registers -1).  I am pretty sure this is not the problem, but just wanted to check.

Yes, you are right I want to write 25 registers.

Greg Hupp said:

In the original post, the array that you included is your data you are writing?  If so, it appears there may be a write issue (timing perhaps) since the above post containing the register read back doesn't appear to match you write array (after RLD_SENSP (0x0D)).  You may want to make sure that all the timing and frequencies are what you think they should be; it could be the first bunch of register writes OK, but by the time you get to RLD_SENSN that you get out of sync on the write operation. 

I have corrected the issue about reading command registers, but when I read Device ID with configuration registers, (RREG1 = 0x20, RREG2 = 0x1A) I read 0x52 which should be 0x92. My problem about data reading is getting strange that I always read the data below:

I am daunted of this SPI reading problem.... Please help me to resolve this.

Regards.

Ekrem -

You should use an oscilloscope or logic analyzer to debug your interface...these are pretty standard pieces of equipment used during debug of embedded system development.  The screen captures you saw were taken with a small, portable logic analyzer, but as mentioned an oscilloscope will work as well.  With these, you can very the timing on your interface to make sure that you are meeting all the timing specs from the datasheet.

You may want to check and verify that you are meeting the decode timing when sending commands to the device.