B
Reaction score
3

Latest activity Postings About

    • B
      Hi Tim, I can't comment about the Teensy4.1 code, since this SoC goes up a level of complexity. I get the impression that it has some kind of pin re-mapping, but that's all I know. Using my code on the Teensy3.5 (but should port to any Teensy3)...
    • B
      I just noticed that for the Teensy3.1, for every "slightly too long" captured value, there is a matching "too short value". Looking at the middle table. Expected value = 46. Pair values 51 and 43. (43+51)/2 => 47. Pair values 56 and 36...
    • B
      I replaced the Teensy3.0 with a Teensy3.1 and re-ran the experiment. Total number of event captured 700 00000 _____ _____ _____ _____ _____ _____ _____ _____ 00008 _____ _____ 00001 _____ _____ _____ _____ _____ 00016 _____ _____ _____ _____...
    • B
      I have made some further investigation. I am now using a Teensy3.5 to generate a sequence of 4us "read-data" pulses and some fake index pulses. See my posting in another thread about using DMA and the PIT timers to stream an 8-bit array to a...
    • B
      Oops forgot to mention. I added some code to DMAChannel.h to support PIT continuous trigger mode. Add around line 477 just below the function void triggerAtHardwareEvent(uint8_t source). // Use a PIT to make the DMA channel run void...
    • B
      Thank you. I have been playing with DMA today on a Teensy3.5 and I have learnt quite a lot. It's not too difficult, however I haven't seen it clearly documented. The datasheet is a bit unclear in my opinion.
    • B
      I have been reading the K64 Sub-Family Reference Manual, and various postings found online. The Teensy3.5 DMA is composed of two parts, the DMAMUX and the eDMA. I would describe the DMAMUX as the thing that selects which module will trigger...
    • B
      // // program top experiment with streaming an 8 bit array to an I/O port using DMA // // Written by badsector/migry // // 20-Dec-2023 : First write taking toggle example code from PJRC forum posting. // - Did eventually see a 500kHz...
    • B
      OK I have spent an interesting day or two trying to understand the operation of the DMA and get something working. I now can stream from a byte array to the lower 8 bits of PORT C (maps to various digital pin numbers). The bottom blue trace...
      • DMA zoomed out.png
      • DMA better method first pulse now OK.png
    • B
      Could you give a pointer to your code please, and title of thread (if applicable) ?
    • B
      You might have given me an idea about a "how do I" thread I started earlier. I am hoping to use a Teensy3.5, so plenty of RAM. I need a continuous single bit stream (it does need to start, run, and then stop). It could be done if I had an array...
    • B
      Continuing my floppy disk read saga.... I would like to understand what methods I might use on a (spare) Teensy 3.5 to generate a data stream which would be used to write floppy data. The idea would be to use this to feed into my Teensy3.1 board...
    • B
      Thank you for your suggestion Chris. I tried adding the suggested change, as follows. // slew rate CORE_PIN11_CONFIG |= PORT_PCR_SRE; CORE_PIN12_CONFIG |= PORT_PCR_SRE; CORE_PIN14_CONFIG |= PORT_PCR_SRE; CORE_PIN15_CONFIG |=...
    • B
      I don't know if I am wasting my time by going down a long rabbit hole.... I am intrigued as to what the problem could be, and my curiosity is to investigate it, even though I have a work flow using the Teensy3.0 and FTDI module for serial...
    • B
      Yes, thank you. That was the posting. I added the asm command, which was after a digitalWriteFast(), so it did follow a hardware write. Unfortunately the problem has not been fixed. :-(
    • B
      Sorry. I don't have a blog or a GitHub. Nevertheless I am very happy to share the code with anyone interested. If you want deeper details/information, probably best to PM me and I will answer ASAP. I kept many of my Atari ST floppies from the...
    • B
      Apologies. Please ignore my "read ZERO" from the FTM. It was a bug in my debug routine in the ISR which records values in an array.
    • B
      NVIC_SET_PRIORITY(fromFDDreadPinIRQ, 0); // HIGHEST priority I am pretty sure that during the track/sector read only the index pulse and read-data can generated interrupts. I switched off the SysTick. Other sources of interrupt, well I'm...
    • B
      const byte fromFDDindexPin = 22; const byte fromFDDreadPin = 21; // PORT-D IRQ #43 const byte fromFDDreadPinIRQ = 43; // IRQ_PORTD = 43, // kinetis.h (Teensy 3.0)
    • B
      I have done some further investigation, looking at the raw data captured from the FTM timer module. I also compared a good data stream against the place where it was corrupted. I tried to line up the re-constructed floppy read pulses, but when I...
    • B
      I would appreciate any pointers (other postings, web sites) as to how to identify all sources of interrupts and the code needed to disable them. The MK20 SoC is a complicated and sophisticated architecture and I am no expert. It's significantly...
    • B
      OK, so I now have a working system (work flow) using the Teensy3.0 (with the needed 96MHz overclock). I searched around and found a FDTI board, the common red type, and likely a Chinese clone/fake. I played around with TeraTerm and flow...
    • B
      Wow! Great. Looks like a really useful little program. Many thanks. For some reason I had problem with Serial starting so I removed the millis() part. I'm pretty sure my board is a Teensy3.0. It has no text indicating this on the bottom of the...
    • B
      A quick update. I have a Teensy3.1, but it needed to be de-soldered from it's current usage. I tried the floppy decode/read and the behaviour was the same as observed on the Teensy3.2. Only about 1 read in 10 returns the correct data. Note: this...
    • B
      Some additional information regarding USB/Teensy3.X/overclock. I replaced the Teensy3.0 board with a Teensy3.1. I re-ran the "serial USB transfer debug" program (all hardware code removed). At 96MHz overclock I got random lock-ups. Serial...
  • Loading…
  • Loading…
Back
Top