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  • PaulStoffregen
    To be honest, I really not sure. I haven't really ever needed to worry about exactly how the ARM core clears the NVIC pending state. It happens automatically somehow, but I can't say from memory exactly how. You'd need to dive into the ARM...
  • S
    Hello. Just seeing if there are any Teensy LC’s out there.
  • S
    shawn replied to the thread Spare Teensy LC's.
    I think I’ll start a new thread… I did see that you had run out, per post #4. For some reason I thought using this thread would be more efficient.
  • PaulStoffregen
    Yes, wires are ok if you keep them reasonably short. Longer than about 4 inches / 10 cm would be risky. Pins 6, 10, 11, 12, 13, 15 are optional. If you leave those off, try running examples like Synth > Guitar which don't use the SD card.
  • KurtE
    KurtE replied to the thread Accessing PSRAM with DMA.
    Hard to say about speed…. Works reasonably when you boost the psram speed up. I am currently playing with it on Nt35510 display 800 by 480, and I have been playing with different number of bytes per pixel. 2,3,4…
  • M
    MAW2732 replied to the thread Spare Teensy LC's.
    I'm shipping out the last of mine today, sorry.
  • S
    shawn replied to the thread Spare Teensy LC's.
    I could use a few Teensy LC’s if anyone has any more.
  • S
    So I noticed that this file (on line 122): https://github.com/PaulStoffregen/cores/blob/master/usb_midi/usb.c It says that adding the AC interface has caused MIDI to fail on Linux. So I guess the AC interface has continually been omitted...
  • M
    MarcoM90 replied to the thread Accessing PSRAM with DMA.
    Thanks for the code! All the buffers will be declared with EXTMEM and passed to the library. Then as stated in the first post, can they be accessed by DMA when sending to SPI, ideally without speed loss?
  • M
    Yes that's fine - although it would be called in-line, not in series as that means something very specific in electronics (!). Keep the wires short and direct if possible to reduce the chance of signal degradation. Any pins not connected will...
  • defragster
    Is this 'pending' the same state cleared when the interrupt service is marked complete on _isr exit? That is if SysTick 'in progress' when the next SysTick triggers it won't interrupt immediately on exit?
  • KurtE
    KurtE replied to the thread Accessing PSRAM with DMA.
    Mst of the libraries, unless you allocate the buffer your self, it will try to use malloc to allocate it. However most if not all, give you and api to set the frame buffer to wherever you want it. One example: tft_frame_buffer = (uint8_t...
  • defragster
    ARM implemented a nice "tail chaining" optimization in the hardware, because it is a common case where 1 or more other interrupts are already pending (at the same or lower priority) when your interrupt finishes. Rather than restoring the...
  • E
    elikl replied to the thread Teensy 4.1 Industrial environment.
    Thank you for fast response. Used only up to 8 hours a day, operate by humans, underwater up to 60 ft sealed in stainless steel sealed house which also is the heat sink. So, what might the problem using your PCB. Did your PCB tested in the...
  • A
    AndyA replied to the thread Teensy 4.1 Industrial environment.
    The processor is not the industrial rated temperature spec version of the part so it depends what exactly you mean by industrial environment. People have made their own Teensy compatible boards using industrial grade versions of the part and...
  • C
    Thanks To PJRC Staff for making Teensy audio Board. I am new one with this. i have placed order for (teensy 4.1 + Aduio board Rev D) .. here i want to ask About wiring connection. If Audio board is being on Teensy with headers , No problem. But i...
    • teensy4 Audio wiring.jpg
  • P
    I have attached the .HEX files from both the working version (with Teensyduino 1.57) and the non-working one (Teensyduino 1.59) if that helps
  • W
    Nah, you just handed me the perfect pass, Mate. It's been a pleasure working with you. Yes, now I'm much more confident about running 1.57b2 on my projector, now. BTW, I used to work for a Cambridge company back in the 1980s, named Laser Point...
  • M
    MarcoM90 replied to the thread Accessing PSRAM with DMA.
    Oh yeah I had already read about it but forgot! Can you also confirm the first question?
  • D
    DrM replied to the thread Teensy 3.2 End Of Life.
    @PaulStoffregen First, aside, Paul have you tried that ADC we talked about somet time ago? That one has a mux and can share one opamp for all of the channels. I will post or send you the design files if anyone is interested, with the...
    • SAR_opamp_R100_cropped.jpg
    • SAR_opamp_RC20x1_currents_cropped.jpg
    • K20-adcinput.png
  • S
    shawn replied to the thread Issues with time_t in printf().
    I meant <cstdio>, not <stdio.h>.
  • E
    Does anybody have a report or story about using the Teensy 4.1 in industrial environment? How reliable the Leensy 4.1? Thanks. Elik
  • A
    Aduen replied to the thread Beware! T4x RTC power consumption.
    I assumed that GPIO pins are not even set nor part of the power off RTC circuit...?
  • PaulStoffregen
    ARM implemented a nice "tail chaining" optimization in the hardware, because it is a common case where 1 or more other interrupts are already pending (at the same or lower priority) when your interrupt finishes. Rather than restoring the...
  • PaulStoffregen
    Every interrupt has a pending bit and a priority level. The priorities are 0 to 255, where 0 is the highest. When the hardware event occurs, the interrupt's pending bit is set. The NVIC (Nested Vector Interrupt Controller) looks at all those...
  • D
    Dogbone06 reacted to KurtE's post in the thread RAM optimization for large arrays with Like Like.
    This thread appears to have a life of its own! Here is my 2 cents worth... Probably worth about that much: If your arrays are initialized as part of the build process and are larger than can fit into RAM1 and as such you need to put them into...
  • D
    Dogbone06 reacted to jmarsh's post in the thread RAM optimization for large arrays with Like Like.
    ITCM now gets flagged as read-only in the MPU so the padding isn't writable.
  • D
    Dogbone06 reacted to defragster's post in the thread RAM optimization for large arrays with Like Like.
    It was always claimed 'Read Only' but worked when last checked with this code last edit Feb 2023. ... // LAST PRINT printf( "End of Free ITCM = %u [%X] \n", ptrFreeITCM + sizeofFreeITCM, ptrFreeITCM + sizeofFreeITCM); // This now causes...
  • D
    Dogbone06 reacted to jmarsh's post in the thread RAM optimization for large arrays with Like Like.
    It is (mostly) transparent; when you fetch a byte from PSRAM, the entire 32-byte cacheline containing that byte will be fetched into the cache. Subsequent reads/writes will use the cache until the cacheline is evicted, either manually or by being...
  • D
    Dogbone06 reacted to theboot900's post in the thread RAM optimization for large arrays with Like Like.
    Any idea how this cache works? I'm assuming it would only cache specific memory that it has accessed. My completely untested theory (and probably wrong) was if you were even accessing only 50% of the items out of order in the array on psram it...
  • D
    Dogbone06 reacted to defragster's post in the thread RAM optimization for large arrays with Like Like.
    A one line CORES edit can make the unused RAM1/ITCM 'padding' available as "READWRITE". In the example above that area is over 30 KB - but can be less than 1KB depending on the build. This risks self(virus)-modifying code or the dangers of...
  • D
    Dogbone06 reacted to defragster's post in the thread RAM optimization for large arrays with Like Like.
    @jmarsh - was it a post you made showing at least one build/source edit that dropped ITCM code by some measurable amount? Having to do with C++ reservation or other [fault or output stubs?]? It would be best to work on building to reduce the...
  • D
    Dogbone06 reacted to defragster's post in the thread RAM optimization for large arrays with Like Like.
    @jmarsh p#37 notes details on the cache - ideally the 32KB cache is designed to most effectively afford efficient access with minimal overreading and only writing back changed blocks. Profiling and use case might show the cache being less than...
  • D
    Dogbone06 reacted to defragster's post in the thread RAM optimization for large arrays with Like Like.
    @Lesept ... @Dogbone06 has put forth a design with 32 MB of SDRAM with PJRC Bootloader. There is a thread or two dedicated to that, as well as some other with display and camera usage. It is based on Teensy MicroMod since it uses a 16 MB Flash...
  • M
    Depends how the interrupt is 'disabled' - if a higher priority is set for interrupts I think it should only defer for when the priority is reduced again, if the individual specific interrupt is disabled in the mask then clearly it should not...
  • M
    MarkT replied to the thread Beware! T4x RTC power consumption.
    Are all pins either OUTPUT or INPUT_PULLUP as required to minimize pad power drain? Floating inputs can drain current.
  • A
    Aduen replied to the thread Beware! T4x RTC power consumption.
    I have recently run into this problem too. What I have found is among the 5 teensy 4.0's I have, the power consumption for the rtc varies wildly. This is measured with no external components for 5 different teensy 4.0's: 2x 92uA, 84uA, 46uA, 27uA...
  • P
    Pio replied to the thread Stereo guitar/bass cabinet emulation.
    Thanks! Slowly getting there. Mouser and Digikey have the AK4558 (and others) in stock at about 5€ in single quantities.
  • defragster
    inclusion of u8x8.setI2CAddress(0x7a);//0x3d x 2 did the trick. Many thanks all!
  • J
    Yes. Think of each interrupt (there's a lot of them on the T4; somewhere around 160 iirc) having three possible states: idle, pending and active. Idle means it is not raised. Pending means it has been raised but the CPU hasn't acted on it yet...
  • S
    shawn replied to the thread Issues with time_t in printf().
    The printf() functions should normally warn you when the parameter type doesn’t match, for example “%lu” and time_t, which should be “%llu”. However, the Teensyduino implementation of the Print interface (which contains a printf(), and is the one...
  • M
    If an interrupt occurs during a period where interrupts are disabled, will it be acted upon immediately when interrupts are enabled? Or is it lost? I suppose this comes down to whether they are edge triggered or level triggered. Example: 1...
  • P
    Thanks for doing all that work Paul - I have definitely benefitted over the last several years, as I have used T3.2's and T3.5's in many of my projects. In particular, my current 4WD robot uses two T3.5's and a T3.2; one of the T3.5's is the...
  • PaulStoffregen
    One of the other changes I recall, but the details of when and which specific versions are now pretty distant and hazy memory, involved changes to the device discovery protocol. The protocol specifies a way for additional info about discovered...
  • P
    OK, in Arduino 2.3.2 'Boards Manager, changing from 1.59.0 to 1.57.3 did the trick. I was able to successfully upload my program to Teensy 3.5 via Joe's wonderful OTA code, and it no longer hangs up. The downgrade process in Boards Manager was...
  • P
    Thanks Paul - I'll give this a whirl tonight and report
  • PaulStoffregen
    Yes. In Boards Manager, 1.57.3 is Teensyduino 1.57. The ".3" means it's the 4th time it's been packaged for Boards Manager (we started with ".0"). It's still the same 1.57 version. Over the last year or so Arduino CLI / IDE has made changes...
  • KurtE
    KurtE replied to the thread Accessing PSRAM with DMA.
    if you use malloc or new, by default these will be allocated in RAM2 This is from the T4.1 product page, in the memory section. If you wish to allocate from the PSRAM, you would instead call extmem_malloc.
    • 1726100695242.png
  • J
    I'm not sure, but if I understand correctly, 1.57.3 would be Beta #3 of 1.57, and not the release version. I still use IDE 1.8.19, so I'm not very familiar with the 2.x stuff. You should probably wait for someone else to reply. Once you get back...
  • M
    Hi all! I have found various topics but I would like a definitive clarification on this: I have to draw to various SPI TFT diplays using the ILI9341_t3n library through DMA. So if I put the TFT buffers into EXTMEM (soldering both chips) will the...
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