3 ms·

Can you imagine if documentation like this was available for modern hardware?! Even something "open" like the raspberry pi doesn't have this level of detail av

Can you imagine if documentation like this was available for modern hardware?! Even something "open" like the raspberry pi doesn't have this level of detail available. The process of deep but accessible technical documentation appears to be a lost art.

deleted 3y ago
[deleted]
joezydeco 3y ago
You're just using the wrong part. If you get an STM32 or NXP iMX, there are tens of thousands of pages of TRM available to describe the function of every block inside the SoC. The core iMX7 technical document is over 7,000 pages. You won't get everything, especially anything ARM has licensed out to the chipmakers like the CPU/NVIC/AHB, but it's a lot deeper than you probably need.
- jakobson14 3y ago
  This. One of the reasons the i.MX series of SoCs shows up so often in open source circles, and elsewhere.
  - joezydeco 3y ago
    i.MX isn't perfect, like there are still closed-source microcode blobs for things like SPI DMA, but it's better than nothing. You can at least build it into a design without having to worry that the supply of boards is being strangled.
RachelF 3y ago
Yep, it is odd that the CPUs on Raspberry Pis have so little documentation.
- joezydeco 3y ago
  It's Broadcom. It's totally normal. The docs exist, you just don't get them unless you're buying massive amounts of raw parts.
jakobson14 3y ago
The Raspi foundation isn't open. Full stop. They don't share schematics. They don't share source code. They barely tell you anything about the custom chip(s) they're now putting in the raspi for GPIO and ethernet/USB. You can't buy them. Hell, they've used custom SoCs made for them by broadcom for years now, which they have exclusive access to. The only "openness" that the raspi foundation engages in is upstreaming of drivers into the mainline kernel and into mesa, which is ultimately self-serving in the end. It reduces the burden on their end of carrying patches for their kernel and ensures other linux distros also pick up some of the slack supporting their products. As for those broadcom chips? get used to it. All modern hardware of any reasonable capability has all the docs sealed behind NDAs that you have to buy a LOT of chips to even get offered. Even then you're expected to take the package deal that the silicon vendor hands you and not invent anything yourself. Chipmakers offer "full ecosystem solutions," not general-purpose parts.

deleted 3y ago

[deleted]

joezydeco 3y ago

You're just using the wrong part. If you get an STM32 or NXP iMX, there are tens of thousands of pages of TRM available to describe the function of every block inside the SoC. The core iMX7 technical document is over 7,000 pages. You won't get everything, especially anything ARM has licensed out to the chipmakers like the CPU/NVIC/AHB, but it's a lot deeper than you probably need.

jakobson14 3y ago
This. One of the reasons the i.MX series of SoCs shows up so often in open source circles, and elsewhere.
- joezydeco 3y ago
  i.MX isn't perfect, like there are still closed-source microcode blobs for things like SPI DMA, but it's better than nothing. You can at least build it into a design without having to worry that the supply of boards is being strangled.

RachelF 3y ago

Yep, it is odd that the CPUs on Raspberry Pis have so little documentation.

joezydeco 3y ago
It's Broadcom. It's totally normal. The docs exist, you just don't get them unless you're buying massive amounts of raw parts.

jakobson14 3y ago

The Raspi foundation isn't open. Full stop. They don't share schematics. They don't share source code. They barely tell you anything about the custom chip(s) they're now putting in the raspi for GPIO and ethernet/USB. You can't buy them. Hell, they've used custom SoCs made for them by broadcom for years now, which they have exclusive access to. The only "openness" that the raspi foundation engages in is upstreaming of drivers into the mainline kernel and into mesa, which is ultimately self-serving in the end. It reduces the burden on their end of carrying patches for their kernel and ensures other linux distros also pick up some of the slack supporting their products. As for those broadcom chips? get used to it. All modern hardware of any reasonable capability has all the docs sealed behind NDAs that you have to buy a LOT of chips to even get offered. Even then you're expected to take the package deal that the silicon vendor hands you and not invent anything yourself. Chipmakers offer "full ecosystem solutions," not general-purpose parts.