jmarsh's latest activity

It's a Fresco Logic 2000DX HDMI dongle. They're designed for USB3 and only 640x480 or 800x600 are usable over USB2 due to bandwidth limitations. Unfortunately, even though the dongle uses an ITE 66121 HDMI encoder there isn't any way to send...

Please post your code.

The USBHost_T36 code has quite a few race conditions, particularly when it comes to handling failed transactions. These have the potential to trigger a crash or infinite loop. This was one of the reasons I wrote my own USB Host library. However...

The USB Host shield you're using is only capable of USB 1.1, not USB 2. That's fine for using it to control the CD drive to play audio (since the audio data doesn't travel over USB) but for actually reading data discs or extracting CD audio it...

I don't want to dissuade you, but I may be working on something more "modern" than VGA...

T4 = Teensy 4.1, pins 10 thru to 13 as they are listed on the PCB and pin diagram. That refers to the timers of the FlexIO module which usually aren't used for any system purpose.

Never mind then. I'll just stick to using my own linker script and FlexSPI2 initialization code (which enabling prefetching, something I filed a PR for nearly 18 months ago) if I'm going to be told to go RTFM when I clearly already have.

FLASH = the default flash, connected to FlexSPI1, fixed @ 0x60000000 ERAM = optional PSRAM and/or flash chip (or MRAM in this case), connected to FlexSPI2, fixed @ 0x70000000

Don't confuse DO with D0 and DI with D1. IO0 = D0, IO1 = D1, IO2 = D2, IO3 = D3. The FTR_CB_101_Sch_pg5 document has the pins on the flash chip labelled incorrectly.

The address isn't configurable, it's fixed for each FlexSPI instance. If writing was going to be done with direct memory access (rather than FlexSPI IP commands like LittleFS currently does) the MPU region mode would probably have to be changed...

You can also just use regular printf or fput functions, by default anything written to stdout or stderr goes to Serial.

This seems like it would be a little bit problematic with the default core behaviour, specifically the smalloc code since it treats the external RAM as a large volatile heap.

You want to be very careful doing that, since Serial itself is a USB device (relying on the usb.c code) and could easily cause a recursive loop or deadlock.

I know the source code is there, I'm asking for a repository so I can file an issue (because whoever wrote it must have access to the documentation for this hardware).

Is there a source repository for Teensyduino's Entropy library somewhere? Seems it doesn't function correctly when the T4.x is running at 24MHz, I'm not sure why because the hardware isn't included in the manual and I can't find anywhere to file...

#include <Arduino.h> or #include <avr/pgmspace.h>

Not without using a customised linker script and modified startup code.

Static uninitialized data should be zeroed. Memory handled by malloc/free is not static, it is dynamic. If you want a dynamic allocation to be cleared when allocated you should explicitly use calloc. If you have int foo EXTMEM; then the value of...

Why? Dynamically allocated memory does not need to be cleared.

This PR includes zeroing PSRAM on startup, but the main aim is speeding up the dynamic allocations: https://github.com/PaulStoffregen/cores/pull/731

It does but it shouldn't; it's a violation of C spec for uninitialized static variables to not be set to zero.