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by cmarrin
Thu Sep 19, 2019 11:17 pm
Forum: Bare metal, Assembly language
Topic: Bare metal BCM43438 Driver
Replies: 24
Views: 5424

Re: Bare metal BCM43438 Driver

I'm really happy to see people taking an interest in this again. I looked into doing this 6 months ago or more and got stuck with the inscrutable code for the WiFi chip. So I said screw it and I started on a different approach. I'm building a little hat with an ESP8266 on it, talking to the RPi over...
by cmarrin
Wed Jan 30, 2019 2:41 pm
Forum: Bare metal, Assembly language
Topic: Circle - C++ bare metal environment (with USB)
Replies: 244
Views: 68439

Re: Circle - C++ bare metal environment (with USB)

@cmarrin Don't understand me wrong, personally I do not have a problem with the GPL. I like the open source idea. I don't fault your choice of languages. My suggestion to move away from GPL was a purely selfish one. My hardline stance against using encumbered licenses is a philosophical one. But I ...
by cmarrin
Wed Jan 30, 2019 2:35 pm
Forum: Bare metal, Assembly language
Topic: Circle - C++ bare metal environment (with USB)
Replies: 244
Views: 68439

Re: Circle - C++ bare metal environment (with USB)

Hey! Who do you think you are? I was just about to debug that :) Thanks so much for looking at my code! And thanks for the solution. Your experience at this level of the code is really valuable. I hope I can get there someday! Your current interrupt handler has a bug it doesn't 8 byte align the stac...
by cmarrin
Wed Jan 30, 2019 8:54 am
Forum: Bare metal, Assembly language
Topic: Circle - C++ bare metal environment (with USB)
Replies: 244
Views: 68439

Re: Circle - C++ bare metal environment (with USB)

Ah, right. GPL is infectious - one of its many maddening qualities. Oh, well, still a great piece of work though. Thanks for the response. Have any components been split off anywhere? It would be great if I could find a complete set of startup and interrupt logic to work with. I'll keep looking.
by cmarrin
Tue Jan 29, 2019 5:20 pm
Forum: Bare metal, Assembly language
Topic: Circle - C++ bare metal environment (with USB)
Replies: 244
Views: 68439

Re: Circle - C++ bare metal environment (with USB)

I was getting very excited about Circle. My own project, Placid (https://github.com/cmarrin/placid) is having some interrupt problems and I thought I could use Circle as an underlying system layer to solve them. You've done some incredible work at the low level with interrupt handling on all the dif...
by cmarrin
Tue Oct 30, 2018 3:27 pm
Forum: Bare metal, Assembly language
Topic: Trouble with SPI
Replies: 1
Views: 1154

Re: Trouble with SPI

Ugh. That was quick. Please disregard this question. The fact that CS was giving back an "impossible" result got me thinking and sure enough, I had the wrong base address for the SPI registers.

Sorry for the noise
by cmarrin
Tue Oct 30, 2018 3:22 pm
Forum: Bare metal, Assembly language
Topic: Trouble with SPI
Replies: 1
Views: 1154

Trouble with SPI

I'm trying to get SPI0 working. I've looked at several examples, most notably dwelsh's SPI02 example. I can compile and run his example, connect my RPi Zero to a Wemos D1 mini running the SPISlaveTest sample and they will talk to each other. But the driver I wrote (based mostly on the example in the...
by cmarrin
Mon Oct 22, 2018 10:55 pm
Forum: Bare metal, Assembly language
Topic: Specs for RPi Zero W Wifi hardware?
Replies: 11
Views: 4125

Re: Specs for RPi Zero W Wifi hardware?

No different than working with an ESP8266. It has firmware that was downloaded to make the interface to an mcu or other really easy, there are various solutions making different (incompatible) interfaces to the ESP8266. Or with an ESP8266 you can write the firmware yourself that is downloaded and r...
by cmarrin
Mon Oct 08, 2018 2:46 pm
Forum: Bare metal, Assembly language
Topic: Specs for RPi Zero W Wifi hardware?
Replies: 11
Views: 4125

Re: Specs for RPi Zero W Wifi hardware?

Here is the link to the linux driver on the chip: https://github.com/raspberrypi/linux/tree/rpi-4.14.y/drivers/net/wireless/broadcom/b43 I know far too little about how wifi actually works to get it working I will have to do some more research before I can come back to this. Thanks. I saw that. Awf...
by cmarrin
Sun Oct 07, 2018 8:03 pm
Forum: Bare metal, Assembly language
Topic: Specs for RPi Zero W Wifi hardware?
Replies: 11
Views: 4125

Re: Specs for RPi Zero W Wifi hardware?

Is this at all similar to the raspberry pi 3 wifi? From what I've read they are, for all intents and purposes the same. Apparently the Zero has an extra control line or something that allows it to transfer data somewhat faster, but I'm assuming that doesn't come into play much. I'm certainly not lo...
by cmarrin
Sat Oct 06, 2018 8:58 pm
Forum: Bare metal, Assembly language
Topic: Specs for RPi Zero W Wifi hardware?
Replies: 11
Views: 4125

Re: Specs for RPi Zero W Wifi hardware?

A bit more information. I've discovered here: http://www.raspberrypi.org/documentation/configuration/uart.md https://www.raspberrypi.org/forums/viewtopic.php?f=62&t=140444#p936754 That UART0 is used to talk to Bluetooth and SDIO (presumably on the pins I mentioned) talks to WiFi. Now I just need to ...
by cmarrin
Sat Oct 06, 2018 6:25 pm
Forum: Bare metal, Assembly language
Topic: Specs for RPi Zero W Wifi hardware?
Replies: 11
Views: 4125

Specs for RPi Zero W Wifi hardware?

I'm making good progress with my Placid kernel (https://github.com/cmarrin/placid). Enough so, in fact that I want to get into some of the more advanced drivers. I spent quite some time with the ESP8266 and having a WiFi connection really simplifies a lot of things in working with the board. So I wa...
by cmarrin
Sun Sep 30, 2018 2:16 pm
Forum: Bare metal, Assembly language
Topic: SD card, emmc and mailboxes
Replies: 3
Views: 1837

Re: SD card, emmc and mailboxes

Thanks for the link. I've been meaning to redo sdcard.c. It's the only code in my tree that hasn't been cleaned up. Your code is much cleaner and more clear. I'll work on getting it integrated.
by cmarrin
Wed Sep 26, 2018 10:41 pm
Forum: Bare metal, Assembly language
Topic: Why does my Raspberry Pi Zero W report that it has 256MB?
Replies: 7
Views: 1524

Re: Why does my Raspberry Pi Zero W report that it has 256MB?

I guess, the firmware file fixup.dat is missing on your uSD card. Without it the firmware cannot relocate the file start.elf in memory. Thanks! That was the problem. Everything worked without it, so I assumed it was an optional file! With its inclusion, I now get: ARMMemory: start=0x00000000, size=...
by cmarrin
Wed Sep 26, 2018 10:26 pm
Forum: Bare metal, Assembly language
Topic: Why does my Raspberry Pi Zero W report that it has 256MB?
Replies: 7
Views: 1524

Re: Why does my Raspberry Pi Zero W report that it has 256MB?

Imperf3kt wrote:
Wed Sep 26, 2018 9:11 pm
Your Pi0w did not come from 2014 as they weren't made until 2017.
Did you perhaps mean the Raspberry Pi model A?
Sorry, I wasn't clear. My Raspberry Pi model B+ is from 2014. That's why I think it probably only has 256MB.
by cmarrin
Wed Sep 26, 2018 6:16 pm
Forum: Bare metal, Assembly language
Topic: Why does my Raspberry Pi Zero W report that it has 256MB?
Replies: 7
Views: 1524

Why does my Raspberry Pi Zero W report that it has 256MB?

I'm working on some bare metal mailbox code. So I decided to test it out by getting some info from the system. I've sent the ARMMemory (0x00010005) and VCMemory (0x00010006) commands and this is what I get back: ARMMemory: start=0x00000000, size=0x08000000 VCMemory: start=0x08000000, size=0x08000000...
by cmarrin
Mon Sep 24, 2018 6:23 pm
Forum: Bare metal, Assembly language
Topic: Bootloader with SD card loading feature working
Replies: 0
Views: 809

Bootloader with SD card loading feature working

I've got an initial version of the bootloader for my Placid project running. This started as code from dwelch which does XModem uploads. The big feature I added was the ability to read a binary from an SD card with a FAT32 file system and run that. When the bootloader comes up it autoloads a file on...
by cmarrin
Fri Sep 21, 2018 4:21 pm
Forum: Bare metal, Assembly language
Topic: SD card, emmc and mailboxes
Replies: 3
Views: 1837

Re: SD card, emmc and mailboxes

Wow, I've made amazing progress, thanks to some code I found here: https://github.com/moizumi99/RPiHaribote This came out of a really great thread I found here: https://www.raspberrypi.org/forums/viewtopic.php?f=72&t=94133&p=656428 I grabbed the sdcard.c code from moizumi's repo, along with its frie...
by cmarrin
Thu Sep 20, 2018 11:14 pm
Forum: Bare metal, Assembly language
Topic: SD card, emmc and mailboxes
Replies: 3
Views: 1837

SD card, emmc and mailboxes

I'm writing a boot loader, based on dwelch's code. I've got it do an XModem load just fine. Now I'd like to do a second stage boot. When the bootloader comes up it waits 5 seconds and then loads a kernel binary from the SD card. At least that's what I want to do. My problem is in finding some good S...
by cmarrin
Tue Sep 18, 2018 8:26 pm
Forum: Bare metal, Assembly language
Topic: Limit on the size of a bare metal program?
Replies: 5
Views: 1961

Re: Limit on the size of a bare metal program?

Agreed about the usefulness of this forum, and of course your work deserves the most credit for getting me this far.

Thanks!
by cmarrin
Sun Sep 16, 2018 6:18 am
Forum: Bare metal, Assembly language
Topic: Limit on the size of a bare metal program?
Replies: 5
Views: 1961

Re: Limit on the size of a bare metal program?

One more post. I think I've found the culprit.I have 2 interrupt sources, the ARM Timer and the mini UART. When setting up each I disable the interrupt line specific to that device in the interrupt peripheral registers (the ones at 0x2000B200). Then I setup all the control registers and then re-enab...
by cmarrin
Sun Sep 16, 2018 5:54 am
Forum: Bare metal, Assembly language
Topic: Limit on the size of a bare metal program?
Replies: 5
Views: 1961

Re: Limit on the size of a bare metal program?

A little more info. I'm convinced now that it's not an absolute limit I'm going over. Seems more like it's a positioning of code or something. Maybe I'm overrunning a buffer, which is sometimes is benign and other times is fatal. For a bit, I was thinking that code optimization might be failing. I w...
by cmarrin
Sat Sep 15, 2018 7:42 pm
Forum: Bare metal, Assembly language
Topic: Limit on the size of a bare metal program?
Replies: 5
Views: 1961

Limit on the size of a bare metal program?

I've been bare metal programming on a Raspberry Pi Zero W for a couple of weeks. It's my own code, but with many ideas from other work, especially that of David Welch. It's been working great. I've added interrupt driven serial input, I'm using the ARM timer to blink the activity LED on an interrupt...

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