Sphere ADC questions

Question

Hello Group,

I have a few questions on how to use an existing Sensor that I have

My questions are:

How to Connect the Sensor to the MT3620?

When Connected, how to access the pins through my program.of the ADC on the MT3620, specifically (CLK, D out, D in, CS/SHDN) ?

I would enjoy getting collaboration support from the group, I am a developer that has a limited knowledge about electronics and MCU's in general.

Regards

Steve

Here is some more background on what I am trying to do, but I'm stuck on getting the sensor hooked up to the Kit

I am trying to connect a Heart Rate Sensor that I have from another project to my Avnet MT3620.

This project is working great for me on a Raspberry PI . Here is the link to the project from the vendor of the Heart Pulse sensor.

https://github.com/WorldFamousElectronics/Raspberry_Pi/blob/master/PulseSensor_C_Pi/PulseSensor_C_Pi.md

I would hope that I can use this project as an example to connect the sensor directly to the MT3620 and port the code to the Sphere SDK.

This project uses the Raspberry PI and circuit on a breadboard. The code is written In C.

The circuit contains an ADC chip that takes a signal from the heart Sensor into an analog input pin on the ADC

Document link: Sphere ADC Document

Message was edited by: Stephen Kruglewicz

skruglewicz · Accepted Answer

A question posed to bwilless Apr 23,

Hi Brian

Hope this finds you well during this pandemic.

I tried to send you a direct message but could not, so I'm sending it here.

I'm hoping you can guide me along here. I tend to lean by using sample projects and have been using both the Advanced Tutorial Avnet Azure Sphere Starter-Kit: Advanced Tutorial .and the all 3 blogs in the Avnet's Azure Sphere Starter-Kit (Out of Box Demo... series. Through studying these project , I have been able to learn a great deal about CMake (config, Build etc.) Debugging, Hardware Config, A7 and A4 programming,on board sensor communication.etc.

Which leads me to my reasons for sending you this message.

For a challenge Beats Per Minute --Home Is Where the Hack Is Chal...
I am using a Heart rate sensor from a Rasberry PI project and would like to use the sensor to connect DIRECTLY to the Avnet kit. I have sent out Inquires to the Azure Sphere group as described here:Sphere ADC Document.and Sphere ADC questions

I have received 2 replies of which one recommends connecting the sensor as quote "Try ADC pin on click dock first,"

I assume he means to Attach the purple signal wire from the sensor to the AN pin on the click header?

I describe this in my Blog Post.

Do you agree?

I'm stuck on the sensor Input now? Once I get that solved I can experiment on reading the sensor input from your examples. Help with that would be very helpful also, but I need to get past getting the sensor connected first..

bwilless Apr 23, 2020 6:51 AM (in response to Stephen Kruglewicz)Hi Stephen,The MT3620 uses some of the GPIO pins for ADC inputs as well. Look at the MediaTek example highlighted below for details on connecting ADC devices to the Avnet Starter Kit.
- Documentation
  - Microsoft documentation on ADC
  - MediaTek FreeRTOS ADC Example
    - This example has great documentation on how to connect an ADC device to the Avnet Starter Kit!
- - - I just looked at this code for the first time and it looks like it's iterating over all the ADC interfaces and reading each
  - Microsoft High Level ADC Example
  - Microsoft BareMetal ADC Example
You could also use an existing Heart Rate example application . . .
- You could also use the Avnet Starter Kit example here, by Jim Flynn, that uses the HeartRate4 click module ($21) on the Avnet Starter Kit.
- This is a working high level application
Hopefully that will get you moving again! Let me know if you have any more questions,Brian

shabaz · Answer

Hi Stephen, According to the datasheet snippet in your post, the MCP3008 uses SPI, and that would need to be configured on the Azure Sphere (i.e. google for 'Azure Sphere SPI' to get detail on this). In short, you'll end up having to check the Azure Sphere documentation to identify which pins relate to the SPI interface, connect those to the MCP3008 and then use code snippets as examples to enable the SPI. If no-one has done this with MCP3008 then the datasheet will need to be consulted to write the code for the Azure Sphere, or code could be attempted to be ported. Also, there are other sensors available too that are more all-in-one, so you don't need to have a separate MCP3008 device. An example is this Maxim pulse sensor board Maxim pulse sensor board which uses an I2C interface. It could be another option depending on your requirements. If you're new to electronics, it's quite important to spend some time reading up (even if it is just the Wikipedia page) on SPI and I2C because they are extremely popular inter-IC communications methods, many devices use them. Also, the Azure Sphere documentation on SPI and I2C would need to be examined, to get familiar with the API (it will be different to the Pi in some ways, since there's no real standard for this like POSIX).

Sphere ADC questions

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