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Type: Posts; User: Bill Greiman

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    Generally you can use libraries in the usual way....

    Generally you can use libraries in the usual way. There can be problems since libraries were not written for a multi-threaded environment.

    Here are some of the problems I have seen.

    You must...
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    All of the SdFs features/code are now in...

    All of the SdFs features/code are now in SdFat-beta. I will not be updating SdFs in the future.

    I will probably add some support for USB drives. I have an example using an Arduino ADK with a...
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    Here is one more test using SPI1, the second SPI...

    Here is one more test using SPI1, the second SPI port.

    I made a test setup with pogo pins connecting to pin 26, MOSI1, and pin 27, SCK1, on the Teensy 4.0 Back Side.

    I used pin 0 for CS1 and...
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    Here is a link ...

    Here is a link to a benchmark that compares uSDHC SDIO, dedicated SPI, and shared SPI on Teensy 4.0 with 512 byte transfers.

    Here is a summary:

    uSDHC, about 22 MB/sec read/write.

    Dedicated...
  5. I recently released SdFat-beta...

    I recently released SdFat-beta with support for the Teensy 4.0 uSDHC pins.

    Here are results for the bench example using uSDHC. About 22 MB/sec read write.


    FILE_SIZE_MB = 5
    BUF_SIZE = 512...
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    I suspect it's mainly for security/reliability. ...

    I suspect it's mainly for security/reliability. The architecture is similar to ARM processors with TrustZone. NXP calls it their "signature EdgeLock security solution".

    The idea is sometimes...
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    I really like this list. For the SD, make...

    I really like this list.

    For the SD, make UHS-I support possible. Here are some requirements from this post.

    The uSDHC supports DDR50/SDR50/SDR104 with 1.8V signaling. I can put an SD in 1.8V...
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    Modern uSD cards can have large current pulses. ...

    Modern uSD cards can have large current pulses. 512KB flash pages are common and write times must be fast to achieve 100 MB/sec rates. so large pulses can occur.

    Here is the spec for for max...
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    ChibiOS/RT RTOS for Teensy 4.0.

    I have updated the ChRt library to release 19.1.3 of ChibiOS and added support for Teensy 4.0.

    Release 19.1.3 is about two years newer than the version I used in the last update of ChRt. There...
  10. T4 - Correct Way to Connect SVC Handler to Interrupt?

    I am porting the ChibiOS RTOS to T4 and need to use the SVC Call vector. Here is the code I am currently using for SVC_Handler and periodic tick.


    static void tick() {
    CH_IRQ_PROLOGUE();
    ...
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    I won't be implementing faster SD modes. T4...

    I won't be implementing faster SD modes. T4 can't support 1.8V signaling. See this.
  12. T4.x with SD socket and 1.8V signaling?

    Looks like fast SD modes are impossible with T 4.0. It would be great if a future version of of T 4.x with a builtin SD supported 1.8V signaling.

    The uSDHC supports DDR50/SDR50/SDR104 with 1.8V...
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    If begin(BUILTIN_SDCARD) works with SD.h on T4...

    If begin(BUILTIN_SDCARD) works with SD.h on T4 then begin(SdioConfig(FIFO_SDIO)) or begin(SdioConfig(DMA_SDIO)) should work with SdFat-beta. The first form is usually fastest.
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    In SD.h Paul defined BUILTIN_SDCARD as 254 to...

    In SD.h Paul defined BUILTIN_SDCARD as 254 to indicate SDIO.

    SD.h has few options and is based on a version of SdFat that I wrote over ten years ago.

    I kept compatibility with sd.begin(csPin)...
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    I experimented with Win10 formatter. If you...

    I experimented with Win10 formatter. If you totally erase a card, it formats the card GUID instead of mbr and is unusable. If the card is mostly OK, it uses the existing layout. Other cases give...
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    It looks like you have a version 1.x of SdFat. ...

    It looks like you have a version 1.x of SdFat. SdFat-beta needs to be in a folder named SdFat and must replace the version 1.x of SdFat.

    This line is unfortunately near rhe bottom of the ...
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    How did you format your card? It doesn't seem to...

    How did you format your card? It doesn't seem to have the standard layout. The SD Formatter does a format that matches the card's flash layout. This allows update of the two FAT tables to be...
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    SdFat SDIO for Teensy 4.0

    I have posted SdFat 2.0.0-beta.3 on GitHub. It supports SDIO on Teensy 4.0.

    It has slightly faster read/write performance on T4 than T3 for larger transfers. This may improve in the future.
    ...
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    No need to enable the debug prints unless it...

    No need to enable the debug prints unless it fails again.
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    If you get an error print please add these...

    If you get an error print please add these additional changes.

    In SDTest.ino add this routine:


    void dbgSdError() {
    if (SD.sdErrorCode()) {
    SD.errorPrint(&Serial);
    while (true) {}...
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    I downloaded the above files. I don't have the...

    I downloaded the above files. I don't have the WIZ850IO so I disabled the section, from about line 83 - 98 of SDTest.ino and change the SD CS for the T4 breakout.

    I ran SD.h for about 300 files...
  22. Happiness - New Cable Fixed Problem

    New cables arrived from Digi-Key. I put the T4 on stacking headers to avoid the kink.

    17557

    Tried Paul's SD.h on SDIO and it worked.


    Initializing SD card...Wiring is correct and a card is...
  23. FFC-8P to 2.54 Through Hole

    I ordered these FFC adapters.

    https://www.amazon.com/SUKRAGRAHA-Connector-Adapter-2-54mm-Through/dp/B07T7FCBVS

    It would be great if Paul would sell a T4 with the FFC connector.

    A little...
  24. My cable had an almost 90 degree sharp bend in...

    My cable had an almost 90 degree sharp bend in the blue stiffener right at the connector. I ordered lots of cables so I will try to do a gentle bend and keep the Pogo pins.

    The new SdFat-beta...
  25. I think I see the problem. Its the cable. The...

    I think I see the problem. Its the cable. The kink in the cable cracked the foil. The kink was extreme and in the blue stiffener.

    When I removed the T4 and pinched the cable flat, the ends of...
  26. I see this is a known problem. ...

    I see this is a known problem.

    https://forum.pjrc.com/threads/54711-Teensy-4-0-First-Beta-Test?p=211858&viewfull=1#post211858

    You can't plug the T4 into it's socket without a bend in the stiff...
  27. I am using the the SDIO socket to develop an fast...

    I am using the the SDIO socket to develop an fast SDIO driver for SdFat.

    This socket works intermittently when I remove the T4 from its connector and pinch the FFC ribbon cable's blue area...
  28. T4 Unreliable Connection with Breakout SD Socket

    I have been using a Teensy 4.0 beta-2 on a breakout board Paul sent. I am using it for development of SdFat.

    Initially the connection to the SD seemed OK. When the breakout arrived, I checked the...
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    Looks like there is no way to correctly mux the...

    Looks like there is no way to correctly mux the SPI pins to the SD socket. It is nice that Teensy 3.5/3.6 allows this.

    SPI access is nice since you can insure the max latency for a write is small...
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    SPI2 and micro SD

    Just received my T4B2. Tried the microSD socket with SD.h and it works with several examples.

    I see that the microSD socket is connected to both SPI2 and the uSDHC controller.

    I decided to...
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    Uhs-i sd

    I assume UHS-I SD cards will be supported. About a year ago I bought a STM32H7 400 MHz Nucleo board with UHS-I 208 MHz support.

    It's really difficult to get even fair DMA performance. UHS-I...
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    Yikes! This is most of high performance...

    Yikes! This is most of high performance computing.

    I started this thread with the misunderstanding that the EventResponder ruled out use of exception vectors for use by an RTOS.

    I understand...
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    I have a better answer to Frank's question. I...

    I have a better answer to Frank's question.

    I have ported the new FreeRTOS V9 to three Arduino architectures. As I expected, FreeRTOS is best as a scheduler so it is not worth mods to the Arduino...
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    Start with this...

    Start with this, then this, and, this.

    Search for "when to use a rtos" with google. Use of an RTOS in embedded systems is very controversial so read several pro and con articles.

    Here is a...
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    Yes I overwrite the vectors. I was trying to say...

    Yes I overwrite the vectors. I was trying to say EventResponder is disabled so you can't use it to solve the problem of making the call look synchronous to the thread by using this call.


    bool...
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    I will describe what needs to happen for an SPI...

    I will describe what needs to happen for an SPI DMA transfer.


    If the SPI call is:


    SPI.transfer(txBuffer, rxBuffer, count);

    When the DMA transfer starts, transfer() must wait on a...
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    Support for FreeRTOS

    I was planning to drop support for my FreeRTOS library. I didn't realize how many people were using my old port. I should have known by looking at GitHub traffic.

    Since there are so many users, I...
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    The answer to what users want in an RTOS is...

    The answer to what users want in an RTOS is simple, FreeRTOS if they can't use Linux. I like other RTOSs much more but I keep getting mail asking me to update my port of FreeRTOS.

    2017 Embedded...
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    I posted an example that replied to your...

    I posted an example that replied to your conjecture that beginners couldn't deal with an RTOS. Did you look at it? It's a real example with real code, not rhetoric.

    Sorry, I should have not...
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    The reason it is no longer used is that the cost...

    The reason it is no longer used is that the cost of developing big systems is now in software. Big systems like LHC use thousands of micro-controllers. There is no longer a place for a clever trick...
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    Beginners have no problems with setting stack...

    Beginners have no problems with setting stack sizes.

    I patched my ChRt library so it will run on Teensy 3.6. This example illustrates how to set stack sizes.

    Here is output:


    The unused...
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    The idea of using an interrupt controller has...

    The idea of using an interrupt controller has been used before in place of an RTOS. You are just 50 years too late to get credit for the idea.

    The first I know of were early NASA flight control...
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    First, a thread is activated when it is the...

    First, a thread is activated when it is the highest priority thread and runable. Threads are not runable while they wait for events. Threads wait on mutexes, semaphores, sleeping for an interval or...
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    The first point, "System code is not thread...

    The first point, "System code is not thread safe". A key function of an RTOS is to handle this.

    I am a bit puzzled, I noticed TeensyThreads has a "Mutex" but it appears to not queue waiting...
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    Wow, Nominal Animal, great insight. There are so...

    Wow, Nominal Animal, great insight. There are so many points here but I will only reply to a few that I think are most important.

    First, the system should start as Arduino and look like Arduino...
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    I have been using the STM32 Cortex-M7 chip for...

    I have been using the STM32 Cortex-M7 chip for almost two years, it was announced mid 2015. It is more than twice as fast as an M4 chip running at the same clock frequency. In a few days I should...
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    No, commandeering interrupts is not the problem. ...

    No, commandeering interrupts is not the problem. This change made me realize that it is not worth porting an RTOS when you get almost none of the new functionality.

    As I said above, the path of...
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    The problems of taking full advantage of a modern...

    The problems of taking full advantage of a modern RTOS in the Arduino environment with new Cortex M7 and multi-processor chips are overwhelming. It's no longer about a scheduler. You need a whole...
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    I assume the same is true for PendSV. void...

    I assume the same is true for PendSV.


    void pendablesrvreq_isr(void)
    {
    EventResponder::runFromInterrupt();
    }

    It's probably time to give-up trying to support an RTOS on Arduino style...
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    RTOS no longer usable with Teensy?

    Looks like EventResponder prevents use of FreeRTOS, ChibiOS and other RTOSs.



    Should I remove Teensy support from ChibiOS/RT, FreeRTOS, and NillRTOS on GitHub?

    I don't see any weak hook or...
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