TinyGo for Raspberry Pi Bare Metal

[Gustavomurta]

There are currently several very interesting Bare Metal Raspberry Pi projects. Using the Rasp Pi as a SUPER microcontroller without an operating system. Very interesting!
https://github.com/smuehlst/circle-stdlib
https://github.com/rsta2/circle

I've already built a synthesizer based on the Yamaha DX7, using a Rasp Pi Bare Metal. Fantastic!
https://github.com/probonopd/MiniDexed

I know it must be quite complex, but my suggestion would be to develop Tinygo to use the Raspberry Pi as a Super Microcontroller.

I'm sure countless professional and industrial applications could be easily developed for the Raspberry Pi using the awesome Tinygo.

[aykevl]

That would indeed be very interesting! So anybody who would like to pick up this project is welcome to do so :)

You can take a look at #1027 for example. I'm not sure why it stalled, probably in part because it's a large patch. It will also need to be rebased to be mergeable.
(Note that every Raspberry Pi SBC is different, and will likely need special support per SBC).

[Gustavomurta]

Processors for Raspberry Pi:
The processors are indeed different, but they have some similarities.

BCM2835
The BCM2835 is the Broadcom chip used in the Raspberry Pi 1 Models A, A+, B, B+, the Raspberry Pi Zero, the Raspberry Pi Zero W, and the Raspberry Pi Compute Module 1

BCM2836
The Broadcom chip used in the Raspberry Pi 2 Model B. The underlying architecture in BCM2836 is identical to BCM2835.

BCM2837
This is the Broadcom chip used in the Raspberry Pi 3 Model B, later models of the Raspberry Pi 2 Model B, and the Raspberry Pi Compute Module 3. The underlying architecture of the BCM2837 is identical to the BCM2836.

BCM2837B0
This is the Broadcom chip used in the Raspberry Pi 3 Models A+, B+, and the Raspberry Pi Compute Module 3+. The underlying architecture of the BCM2837B0 is identical to the BCM2837 chip used in other versions of the Raspberry Pi.

BCM2711
This is the Broadcom chip used in the Raspberry Pi 4 Model B, Compute Module 4, and Pi 400. The architecture of the BCM2711 is a considerable upgrade on that used by the SoCs in earlier Raspberry Pi models. It continues the quad-core CPU design of the BCM2837, but uses the more powerful ARM A72 core.

BCM2712
Broadcom BCM2712 is the 16nm application processor used in Raspberry Pi 5, Compute Module 5, and Pi 500. It is the successor to the BCM2711 device used in Raspberry Pi 4, and shares many common architectural features with other devices in the BCM27xx family, used on earlier Raspberry Pi products.

Reference:
https://www.raspberrypi.com/documentation/computers/processors.html

[Gustavomurta]

Searching on Github I found this project. But I haven't tested it yet.

TamaGo is a framework that enables compilation and execution of unencumbered Go applications on bare metal AMD64/ARM/RISC-V processors.

https://github.com/usbarmory/tamago

[Gustavomurta]

My dream project (using TinyGo):
A cheap and super powerful logic analyzer (Raspberry Pi Zero or higher - Bare Metal).

• 16, 32 channels or more
• Sample rate 100 Msps or more
• Sample memory 512 MB.

I have no programming experience - just the basics.

I recently discovered an amazing and little-known feature of the Raspberry Pi - Secondary Memory Interface - more than 16-bit fast direct bus. The SMI interface has up to 18 bits of data, 6 address lines, read & write select lines.
https://iosoft.blog/2020/07/16/raspberry-pi-smi/

DMA will be useful too:
https://iosoft.blog/2020/05/25/raspberry-pi-dma-programming/

[Gustavomurta]

I've been testing the Circle project and I'm increasingly impressed by the Raspberry Pi's ability to function as a Super Baremetal Microcontroller!

https://github.com/rsta2/circle

For example (the old model I have here at home):
https://www.raspberrypi.com/products/raspberry-pi-zero/

• 1GHz single-core CPU
• SD card slot (to run firmware)
• 512MB RAM
• Mini HDMI® port
• Micro USB OTG port
• Micro USB power
• HAT-compatible 40-pin header

All Raspberry Pi models:
https://www.raspberrypi.com/products/

[Gustavomurta]

I'm testing programming support using GDB via serial port. The Circle GDB project isn't mature yet, but it worked in my first test. I'm researching other options.
https://github.com/farjump/Alpha_Raspberry_Pi_Circle

Unfortunately, the Raspberry Pi's JTAG interface is multiplexed across the GPIO pins, making it not very user-friendly.
https://sysprogs.com/VisualKernel/tutorials/raspberry/jtagsetup/

This GDB project is old but it works perfectly.
https://github.com/farjump/raspberry-pi

" GDB offers the best embedded software development experience by allowing you to remotely load, debug and test your programs and hardware/software interfaces. It feels like native programming thanks to a similar smooth "Edit-Compile-Run" cycle.

Alpha server (aka "gdbstub" and "gdb stubs") allowing you to dynamically debug anything running in your hardware target, from bare metal software to OS-backed programs, including their threads, the underlying drivers, etc. All with a single GDB session and without any JTAG probe."

[Gustavomurta]

I know it's very complex, but how do I start a project to integrate a Raspberry Pi into the awesome Tinygo?

I'm going to study and take tests.
#1027
#1048

Much information about Broadcom's chips is not readily available. But I think the information that already exists is a good starting point.

https://www.raspberrypi.com/documentation/computers/raspberry-pi.html

https://datasheets.raspberrypi.com/