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nRF52840 Feather board Digital Input pins
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nRF52840 Feather board Digital Input pins

by Orvasson on Thu Mar 11, 2021 9:14 am

Hello everyone,

I am really new to the world of MCUs and how to use them. I got a project as my thesis in which I decided to use the nRF52840 feather board and the ADS1294 sensor to achieve an ECG and trasnmit the data to an app through BLE.
Checking the nRF52840 datasheet I had the impression that there is multiple SPI pins. On the nRF52840 Feather board I can see only 6 Analog Input pins, but my sensor(ADS1294) is taking analog inputs and converts (via delta-sigma ADC) to digital output. My question is can I use the Analog Inputs Pins and connect the sensor I want?
I am also thinking of adding an external Flash Memory, how can I determine how much memory can the board support?

Thanks everyone in advance!
Orestis V.

P.S.
I am pretty sure I posted this on the wrong section of the forum, how can I move it?

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Re: nRF52840 Feather board Digital Input pins

by adafruit_support_carter on Thu Mar 11, 2021 11:47 am

Hello. I moved your topic to the General Project Help forum. Agree it's not an Adafruit IO related question.

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Re: nRF52840 Feather board Digital Input pins

by Orvasson on Fri Mar 12, 2021 3:18 pm

Hello everyone,

If anyone has an answer about the SPI interface that would be great.
I have another question about the nRF52840 Feather board, in the Pinout guide it is stated that with a pullup resistor I can work with I2C pins. In which pins should I connect the pullup resistor so I can use it as an I2C pin?

Thanks in advance!
Attachments
I2C nrf52840.jpg
I2C nrf52840.jpg (36.59 KiB) Viewed 167 times

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Re: nRF52840 Feather board Digital Input pins

by adafruit_support_mike on Fri Mar 12, 2021 11:29 pm

Orvasson wrote:Checking the nRF52840 datasheet I had the impression that there is multiple SPI pins. On the nRF52840 Feather board I can see only 6 Analog Input pins, but my sensor(ADS1294) is taking analog inputs and converts (via delta-sigma ADC) to digital output. My question is can I use the Analog Inputs Pins and connect the sensor I want?

Those are two different solutions.

The ADS1294 has eight analog input channels, each with its own ADC. If you use that, you can get readings from all eight ADCs through the SPI interface.

The nRF52480's analog pins connect to a single ADC through a multiplexer. Using those to read input voltages would be an alternative to using the ADS1294, not something that involves both the chip and the analog pins.

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Re: nRF52840 Feather board Digital Input pins

by Orvasson on Sun Mar 14, 2021 7:26 am

adafruit_support_mike wrote:
Orvasson wrote:Checking the nRF52840 datasheet I had the impression that there is multiple SPI pins. On the nRF52840 Feather board I can see only 6 Analog Input pins, but my sensor(ADS1294) is taking analog inputs and converts (via delta-sigma ADC) to digital output. My question is can I use the Analog Inputs Pins and connect the sensor I want?

Those are two different solutions.

The ADS1294 has eight analog input channels, each with its own ADC. If you use that, you can get readings from all eight ADCs through the SPI interface.

The nRF52480's analog pins connect to a single ADC through a multiplexer. Using those to read input voltages would be an alternative to using the ADS1294, not something that involves both the chip and the analog pins.


Thank you for your response.
As I see in the Pinout guide (https://learn.adafruit.com/introducing- ... er/pinouts) the SPI interface is located in the bottom right corner but I do not see a PIN. How do I use this interface?
And can I configure somehow any pins in order to make multiple I2C connections?

Thanks in advance for your time.
Orestis V.
Attachments
circuitpython_nRF52840_QSPI.png
circuitpython_nRF52840_QSPI.png (601.95 KiB) Viewed 157 times

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Re: nRF52840 Feather board Digital Input pins

by adafruit_support_carter on Mon Mar 15, 2021 2:17 pm

Can you clarify what you mean by "PIN". Not sure what you are looking for here.

Both SPI and I2C allow more than one device on the same bus (pins). Is there a reason you actually need more than one bus?

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Re: nRF52840 Feather board Digital Input pins

by Orvasson on Tue Mar 16, 2021 9:34 am

adafruit_support_carter wrote:Can you clarify what you mean by "PIN". Not sure what you are looking for here.

Both SPI and I2C allow more than one device on the same bus (pins). Is there a reason you actually need more than one bus?


Hello again and thank you for your time and response.
I am sorry if I am confusing you because I am a newbie on the terms I use.
I had checked the ESP32 S2 Saola board which had 4 Pins for the SPI interface(MISO, SCK, MOSI,SS) so I was searching for something similar on the nRF52840 board here.
So if I want to connect 3 sensors to the board via I2C I can achieve that by connecting all 3 sensors on the SCL-SDA pins?

Thanks for your time.

Orvasson
 
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Re: nRF52840 Feather board Digital Input pins

by adafruit_support_carter on Tue Mar 16, 2021 10:30 am

The I2C pins are SCL and SDA.
The SPI pins are SCK/MO/MI.

I2C and SPI are two different options for connecting sensors. Both allow multiple sensors on the same bus.

I2C requires each sensor have a unique address.

SPI requires each sensor have a dedicated chip select pin.

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Re: nRF52840 Feather board Digital Input pins

by Orvasson on Tue Mar 16, 2021 1:41 pm

adafruit_support_carter wrote:The I2C pins are SCL and SDA.
The SPI pins are SCK/MO/MI.

I2C and SPI are two different options for connecting sensors. Both allow multiple sensors on the same bus.

I2C requires each sensor have a unique address.

SPI requires each sensor have a dedicated chip select pin.



Thank you very much, you have been really helpful!
I had misunderstood the principals behind I2C and SPI.
Thank you again !

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