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  • Bill Greiman's Avatar
    10-07-2019, 03:23 PM
    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 protect access to...
    4 replies | 369 view(s)
  • Bill Greiman's Avatar
    10-06-2019, 01:39 PM
    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 USB hard drive and...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    10-05-2019, 06:25 PM
    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 pin 1 for MISO1. ...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    10-05-2019, 01:46 PM
    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 SPI, about 3.7 MB/sec...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    10-04-2019, 07:38 PM
    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 bytes write speed and...
    4 replies | 202 view(s)
  • Bill Greiman's Avatar
    10-04-2019, 04:10 PM
    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 called "Silicon...
    87 replies | 4193 view(s)
  • Bill Greiman's Avatar
    10-03-2019, 07:41 PM
    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 mode with the uSDHC....
    87 replies | 4193 view(s)
  • Bill Greiman's Avatar
    10-03-2019, 06:16 PM
    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 current : 6.6.3 Current...
    111 replies | 4682 view(s)
  • Bill Greiman's Avatar
    10-03-2019, 04:03 PM
    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 are many new features...
    4 replies | 369 view(s)
  • Bill Greiman's Avatar
    09-27-2019, 07:10 PM
    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(); chSysLockFromISR(); ...
    1 replies | 88 view(s)
  • Bill Greiman's Avatar
    09-21-2019, 05:39 PM
    I won't be implementing faster SD modes. T4 can't support 1.8V signaling. See this.
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    09-21-2019, 04:20 PM
    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 signaling. I can put...
    0 replies | 95 view(s)
  • Bill Greiman's Avatar
    09-19-2019, 11:28 PM
    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.
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    09-19-2019, 10:24 PM
    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) for simple SPI but...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    09-19-2019, 08:02 PM
    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 various less than...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    09-19-2019, 07:49 PM
    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 README.md on GitHub. To...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    09-19-2019, 07:08 PM
    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 interleaved with writes...
    19 replies | 719 view(s)
  • Bill Greiman's Avatar
    09-19-2019, 06:12 PM
    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. Here is the bench...
    19 replies | 719 view(s)
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ChibiOS/RT RTOS for Teensy 4.0. 10-07-2019 03:23 PM
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11-07-2012