ADS 1293 out of range error

Hello,

What is the value of the ERROR_MISC register (address 0x1E)?

Is it possible to power the patient simulator with batteries? If the simulator is powered from an AC/DC adapter it may not allow it to "float" and be driven by the RL electrode to the appropriate common-mode voltage range of the ADS1293.

Thanks,

Sergio

Hi Sergio,

The values of Error_Misc Register and all the other error registers including Error_Lod, Error_status and error_sync are 0x00. Also patient simulator is powered with batteries not from an AC/DC adapter. 

What does Error_Range1-2-3 registers tell me? What are these out of range errors related to?

Thanks.

Busra

Hi Sergio,

I measured the DC voltage at IN1-2-3-4-5 and I came out with 1.5V. However, I also measured 0.9V at the same pins.

I send the schematic of ADS 1293 in my circuit. (See below)

6567.ads1293_circuit schematic.pdf

Thanks for the quick replies.

Hi Busra,

Is there a hardware connection from the RLDIN pin to the RLDREF pin (pin 11 to 12)? It appears there isn't in the schematic. If this is the case, the RLDIN pin can be connected internally to the RLDREF pin in register 0x17.

Set the register to the following: address 0x17 = 0x05

There is a quick check that you can use to verify correct reading of data. Instead of connecting the channels to external signals, you can use the test bits (TSTx) in the FLEX_CHx_CN registers. These control bits [7:6] override the channel connection and instead can connect each channel to a positive, a negative or a zero differential voltage. The positive and negative voltages are around +0.2V and -0.2V respectively.

The other parts of the ADS1293 circuitry look okay. I am not familiar with the CC2541, but as long as this circuit is the same as in the reference design I don't see a problem.

Regards,

Sergio

Hi Sergio,

Since there is no hardware connection between RLDIN and RLDREF, I set the address 0x17 to 0x05 as you suggested. 

I set TST1=11 for channel 1,  TST2=11 for channel 2 and TST3=11 for channel 3. I did not change the other configurations in 5-lead ECG application (setting address steps in page 41-42). Then I tried to read addresses from 0x37 to 0x3F, the values are all 0x00 and error registers are as follows:

Error_Range1 = 0x01;

Error_Range2 = 0x35;

Error_Range3 = 0x01;

Error_Status = 0x02 for the first reading, it changes to 0x00 for the second reading

Error_Misc = 0x02; 

(I meant debugging by first and second reading. There is a breakpoint at the error register reading part of the code.)

According to Table 5 and Tabale 8 in the datasheet and my R2(5) and R3(6 for CH1 CH2 CH3) settings, ADCmax = 0xB964F0 so I should read 0x5CB278 for ADCout (half of ADCmax). I suppose, ADCout here is representing ECG values in 0x37 - 0x3F?

Now I have a RLDRAIL error. What do you suggest?

Thanks,

Busra

Hi Sergio,

I have an another question for you : You suggested me to measure voltages of IN1-2-3-4-5 and I came up with 1.5V which is below of your guess. What does it mean? I'm measuring them right now and I came up with different values which are 0.7 V, 3.3 V and 100 mV (almost 0) in each pin. 

Thanks,

Busra.

Hi Sergio,

I found the solution. The last step of register settings in the datasheet (see page 41-42) is wrong. It says:

15. Set address 0x01 = 0x01: Starts data conversion.

As I read forums, it should be 

15. Set address 0x00 = 0x01: Starts data conversion.

When I try in this way it works :)  Thanks for put up with me and my questions :)

Have a good day.

Busra

I'm glad you got it working.

You have a good day too,

Sergio

It's not about this topic but I have a question about the ADS1293, when the datasheet says "output data rate: 853 sps", thats means the AD1293 has a sample frecuency of 853 Hz ?

That sample rate is for each lead or for the 3 of them?