rpi-open-firmware: open-source VPU side bootloader for Raspberry Pi

Re:rpi-open-firmware: open-source VPU side bootloader for Ra... by blacksmith_tb on Wednesday February 24, 2021 @11:49PM (#26259815)

Hmm, I can see your point, but only so far - 'existing general computing' like an old x86 laptop gathering dust doesn't have GPIO, for example. Personally I avoid Arduino because even though it's sizzling fast compared to a $15 RPi Zero W I'd much rather be able to use Python or Ruby, and have handy things like networking for api calls, ntp, etc.

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Re:rpi-open-firmware: open-source VPU side bootloader for Ra... by penagwin on Wednesday February 24, 2021 @11:52PM (#26259835)

> Arduino because even though it's sizzling fast compared to a $15 RPi Zero W

Wait are we talking about the arduino uno/nano/pro? Because those are far slower then the raspi zero w, with a magnitude less memory.

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Re:rpi-open-firmware: open-source VPU side bootloader for Ra... by SilverRed on Thursday February 25, 2021 @12:52AM (#26260128)

Depends what kind of speed you are talking about. The Arduino boards are real time while the rpi is not. The rpi can do a larger number of calculations in total but it can not flip the gpio pin timed to a fraction of a millisecond like the arduino can because there is a kernel and scheduler in the way.

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Re:rpi-open-firmware: open-source VPU side bootloader for Ra... by TickleSteve on Thursday February 25, 2021 @03:49AM (#26260981)

You can do bare-metal on the RPi also, you don't have to use a (non-realtime) OS like Linux which is where your latency issues come from. You can treat the RPi as a microcontroller and program it via JTAG, etc if you like. Latency issues come from the OS, not the hardware.

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Re:rpi-open-firmware: open-source VPU side bootloader for Ra... by cleverca22 on Thursday February 25, 2021 @12:43PM (#26265615)

yeah, you can either do baremetal arm under the official firmware (quad-core arm, up to 1.8ghz depending on the model)

or you can do baremetal VPU and skip the firmware entirely 500mhz dual-core VPU 128kb of L2 cache for both code and data if you want dram, you need the ram drivers (only present for the VC4 line, pi0-pi3) you could optionally rely on 1 closed stage to bring ram up, and do baremetal VPU from the start(4).elf to avoid the dram init sequence

and if you build upon rpi-open-firmware, you could get all 6 cores baremetal, running custom code

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