Task Owner:

Who owns this task and will approve the final deliverables? Lazar

Objectives & Goals:

1. How does this task relate to the value track(s)?

- All of the effort we put into improving our product lines should provide value to our customers.
- We need to be able to clearly articulate the value each improvement will provide in the following three value tracks:
    1. Development - The hardware chapter is important for evaluating the Omega modules for a new project and supporting developers in the development process.
    2. Deployment
    3. Production

2. Create a short statement explaining the objectives and goals for this ticket.

Intro

This article cover the SPI port

Context

The Serial Peripheral Interface (SPI) is a four-wire synchronous communication protocol, largely used to connect microprocessors or microcontrollers to sensors, memory, and other peripherals. SPI is a synchronous data bus, meaning that one of the lines is a clock, used to synchronize the bits being sent on the data lines. The protocol is based on the Master-Worker architecture.
- The Master will generate the System Clock and the Chip Select signals
- Each worker requires its own Chip Select connection to the Master.

Hardware

One SPI interface is available.
- The interface supports half-duplex transmissions and can operate in host-mode only
- The maximum SPI clock frequency is 40 MHz
- The flash storage occupies SPI Chip Select 0 and cannot be used, external devices can be connected to SPI Chip Select 1.
- External devices connected to the SPI bus can affect the boot sequence under certain conditions. Refer to special pins-SPI pins for details
Pinout diagrams of Omega2, Omega2S with SPI pins and CS1 highlighted

Software

SPI interface available at /dev/spidev0.1
- spidev0 is the Omega2’s SPI bus number.
- 1 indicates the device ID. This corresponds to the worker connected to the Omega2’s CS1 pin.
Interacting with the SPI bus
- Python
  - Recommended module: python3-spidev
  - For installation and usage instructions see: https://github.com/OnionIoT/python-spidev#python-spidev

Reference Material:

1. Provide hyperlinks for helpful and related information.

Note Please refer to the device tree article and ensure each article has unique content related to the chapter. One article is discussing SPI from the hardware point of view and the other is covering the device tree aspect of SPI so there should not be any duplicate content.

https://github.com/OnionIoT/documentation/issues/66

Refer to the original article

Deliverables or Desired Outcome:

1. What are the task owners expectations?

Articles should be succinct, and minimalist.
These are MVP articles, and we will expand on them as users provide feedback and requests.
All articles from the Hardware chapter will go in the hardware branch.

2. What does the task owner require for a successful completion of the ticket?

i.e. sample code, drawings, documents etc.
a succinct article that follows our current style guide based on the original article

Date Required By:

1. When is the scope required to be completed?

no date has been specified

2. Is this a hard date? Specify if the task is a dependency of another task or if it will impact a customer requirement.

Ticket #44 has a dependency on this ticket to be completed

remingtontr commented 3 months ago

Ready for initial review.

amsiotdeveloper commented 3 months ago

@remingtontr good work!! No suggestions for revisions from me.

@greenbreakfast this article is ready for your final review.

This article is very basic, so I think in future after the MVP is done we might want to include some of the more advanced details of the SPI bus like clock polarity, idle hi/low etc. This is certainly a more advanced topic but necessary when trying to interface with various types of SPI devices. This is good enough for now though.

greenbreakfast commented 2 months ago

@remingtontr added 2 comments, otherwise looks good