ADS1299 Wiring & Start

Hi Till,

Apologies for the delay in getting back to you!  Have you made any headway here?  Is is possible for you to send along a screen shot (O-Scope or Logic Analyzer) of the communication interface to us?  The code sequence above seems OK, but it's often easier for us to just review the actual SPI data transmitted from your host without having to dig through the peripheral details.

Hi Tom,

no Problem! Since my Scope is still broke and i won't have it back until two or more weeks, i didn't make any progress here. I'll post the images once my osci arrived. Thanks & Greetings

Till

Hey, 

now i have another scope. Since i only have two channels, what would be interesting to see? 

Until now i couldn't get any Answer from the chip.

Greetings

Till

EDIT:

Here is a picture of the SPI Clock (blue) and the SDATAC Command.

Hello,

i´m still unable to get any response from the chip. Is there anyway to check if the chip is working?

Would it be possible to samlpe another chip if this one doesnt work?

Greetings

Any Idea? I'm still stuck with this chip. I'm can see my device sending the commands but there is just no answer from the chip. I'm pretty sure about the wiring & just want to know if the execution of the code above should give me an answer from the device or if there is somethin wrong with the routine. What oscilloscope image would help you? 

Greetings 

Till

Ok,

some more Details.

Im Using a Raspberry Pi to connect to the ADS1299. Basicly its the bcm2835. Because i didnt want to write my own spi kernel Driver i used the spi-dev together with this very simple library: http://www.airspayce.com/mikem/bcm2835/index.html 

I rewrote the Code in C to make it more understandable. I also double checked the whole wiring. Nevertheless i`m not able to read a register.

I would be very glad about any suggestions.

Greetings

Till Sellschopp

//----------------------------------------------------------------

#include <bcm2835.h> //Library for the bcm2835
#include <stdio.h>
#include <stdlib.h>

//define GPIO PIN Numbers

#define RESET RPI_GPIO_P1_11
#define PWDN RPI_GPIO_P1_12
#define START RPI_GPIO_P1_15
#define DRDY RPI_GPIO_P1_16
#define CLKSEL RPI_GPIO_P1_18
#define SDATAC 0x11

//------------------------------------------------

int main(int argc, char **argv){

          //load library

         if((bcm2835_init())<0){
                printf("Could not load the bcm2835 library \n");
                exit(1);
         }
         printf("Library loaded \n");

         //Set GPIO Pins to Output

         bcm2835_gpio_fsel(RESET,BCM2835_GPIO_FSEL_OUTP);
         bcm2835_gpio_fsel(PWDN,BCM2835_GPIO_FSEL_OUTP);
         bcm2835_gpio_fsel(START,BCM2835_GPIO_FSEL_OUTP);
         bcm2835_gpio_fsel(DRDY,BCM2835_GPIO_FSEL_OUTP);
         bcm2835_gpio_fsel(CLKSEL,BCM2835_GPIO_FSEL_OUTP);

         //initiate SPI
         bcm2835_spi_begin();
         bcm2835_spi_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST);
         bcm2835_spi_setDataMode(BCM2835_SPI_MODE1);
         bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_65536);
         bcm2835_spi_chipSelect(BCM2835_SPI_CS0);
         bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS0, LOW);

         // POWERUP Sequenz S.58, FIG 56
         // ALL INPUTS LOW
         bcm2835_gpio_write(RESET,LOW);
         bcm2835_gpio_write(PWDN,LOW);
         bcm2835_gpio_write(START,LOW);
         bcm2835_gpio_write(DRDY,LOW);

         bcm2835_gpio_write(CLKSEL,LOW);
         // CLKSEL -> 1 , wait
         bcm2835_gpio_write(CLKSEL,HIGH);
         bcm2835_delay(500);
         // PDWN -> 1, RESET -> 1, wait 1s
         bcm2835_gpio_write(PWDN, HIGH);
         bcm2835_gpio_write(RESET,HIGH);
         bcm2835_delay(1000);
         // RESET PULSE
         bcm2835_gpio_write(RESET,LOW);
         bcm2835_delay(50);
         bcm2835_gpio_write(RESET,HIGH);

         printf("Power-Up Done \n");
         bcm2835_delay(50);
         // send SDATAC
         int error;
         error = bcm2835_spi_transfer(SDATAC);

         printf("SDATAC sent \n");

         //set Internal Reference
         char write[] = { 0x43 , 0x00 , 0xE0 };
         bcm2835_spi_transfern(write, sizeof(write));

         printf("Internal Reference set \n");

         //Read Register
         char read[] = { 0x20 , 0x00 };
         bcm2835_spi_transfern(read, sizeof(read));
         printf("Data Read: %X , %X \n", read[0], read[1]);
         //Close Device
         bcm2835_spi_end();
         bcm2835_close();
         printf("bye bye \n");
         return 0;
}

Good Day again. I'm not sure if my Question is stupid or to much to ask for, but i would apreciate a comment on this topic. Here are some Scope images..

SDATAC

Set internal Reference:

Read Register:

and nothing on the MISO....

anyone, anything? ....

Hi 

Have a look at the other signals on the SPI interface there is SPI_in and SPI_out (which have you shown on the graphs?) What is the START signal and the CE signals doing??

Hi,

the Graphs show the MOSI (Data in of the Chip) and the Clock. There is no signal on the Data out (MOSI) line. For testing i have the Chip Select permanently at GND and the START Pin is LOW during the Transmission.

Thanks & Greetings

Till

Hey Cosmin,

thanks a lot! This solved everything & its working now :-)

Greetings

Hi Till,

I wanted to do same, do you have final code somewhere shared?

It will be very helpful for me.

Thanks,

Ali

Hey,

i do this for my thesis and my university does not allow me to publish anything before I finish the work. Afterwards I will share the Thesis and the whole code on a git repo. The code I posted above (in C) is basically working. I can try to help you if you have questions.

Greetings

Thanks.

Hello Chuchaki,

is your thesis finished well?

Can you now post your Code.

May hep to solve problems.

Regards

Hi Chuchaki

I'm very interested in your thesis as well, please let me know if you publish the results. 

I have 2 questions. 1. Once you run the power-up sequence, could I program the ADS1299 normally with spi? Is entirely necessary the power-up sequence? and 2. How can I visualize the output of the signal as you show in the scope? Is it through SPI out or how is it? 

Thanks, regards.

Felipe

Hey Felipe,

excuse for the huge delay. I was backpacking through Latin-America for some time. If  there still is interest in code and thesis, i can create a git repository and do kind of an HowTo. Would take a little, but i would do that. The Thesis is written in German and currently i wont have the time to translate it. But i can upload it too. 

About your questions: 
1) The Power Up Sequenze is entirely necessary to guarantee a porper boot of the device.  And after the boot you can read and write the register as well as start and read measurement via SPI.
2) To Display the Communication I used a logic analyser from Saleae. Great little device by the way ;-)

Let me know if someone is interested in a git repo. 

regards,

Till

Hello Till,

a posibility to read your theses would be nice. Also a How To is great idea.

I am still interested and seeking up every information about ADS129x I can get.

regards,

Melanie

Hi Meanie,

These people are working on ADS1299 and Arduino and have some code here. You may need to tweak it for Raspberry PI

https://github.com/OpenBCI

And also here.

https://github.com/conorrussomanno/ADS1299 

Thanks,
Ali