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Type: Posts; User: Citabria

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    I traced out the part of the LED circuit visible...

    I traced out the part of the LED circuit visible on the board. I'm not sure there are 4 LEDs nor what V+ voltage is. I measured the voltage across the 8.2 Ohm resistor as 0.40 V, so the LED current...
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    I see now someone else has branched the library...

    I see now someone else has branched the library and made the changes:
    https://github.com/mjs513/NXPMotionSense

    Thanks!
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    I found two workarounds. First, just #define...

    I found two workarounds. First, just
    #define private public which is naughty.

    Second, make local copies of the functions
    bool MPL3115_read(int32_t *altitude, int16_t *temperature)
    static bool...
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    Prop Shield Altimeter

    I see a function in the NXPMotionSense library to read altitude from the pressure sensor, but it's private:

    private:
    void update();
    bool FXOS8700_begin();
    bool FXAS21002_begin();
    bool...
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    Can't find it now but I remember someone posted a...

    Can't find it now but I remember someone posted a schematic clip with a transistor driver for the blacklight. That would make sense if 3.8 mA is the base current, so I'm not measuring the LED current.
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    Oops, missed a decimal point! It's only 3.8 mA. I...

    Oops, missed a decimal point! It's only 3.8 mA. I also tried 69 ohms and got .26 V, and 43 ohms gave .17 V. That's still just 3.8 mA and I saw no change in brightness. Wow, does the board have a...
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    I got the V1.2 board and used the recommended 100...

    I got the V1.2 board and used the recommended 100 Ohms to Vin. I measure 0.38 V drop at 4.84 V, so 38 mA to the backlight LEDs. Are the LEDs in series or parallel? Do we know their current limit? A...
  8. My app includes a filled rect which must move...

    My app includes a filled rect which must move left and right one pixel at a time. The simplistic way to move it is to call fillRect with background color and call it again with new coordinates and...
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    Also, is there any plan to CE certify Teensy LC?

    Also, is there any plan to CE certify Teensy LC?
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    Thank you very much for the thoughtful reply.

    Thank you very much for the thoughtful reply.
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    Expected Lifetime of Teensy LC Product

    I need a 5V digital output and I see Teensy 2.0 is scheduled to be discontinued next year.

    How much longer is Teensy LC expected to be manufactured?
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    Here are the source files. Not pretty, but...

    Here are the source files. Not pretty, but commented at least, so you can follow it.

    It's built on Arduino 1.8.13, Teensyduino 1.53, and SDFAT library 1.1.4.
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    That's me. Saw your post there. Sorry, didn't...

    That's me. Saw your post there. Sorry, didn't connect.

    Here's the Z80 side of the code, not quite pretty:

    const char trmld[] = { // Z80 code TRMLD:
    0x3E,0x0C, //TL LD A,FF
    ...
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    Thanks! Yes, I wrote the Z80 code which works...

    Thanks!

    Yes, I wrote the Z80 code which works as described above: "In operation, Teensy repeatedly transmits a small piece of Z80 code, the terminal/loader, along with the required 5-second...
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    This simulator implements the Exidy tape file...

    This simulator implements the Exidy tape file format, so it's not directly portable to other systems. However, it could be adapted. I don't know C64 nor Spectrum well, but I suspect there are already...
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    In model II (48K) Sorcerers, the cassette...

    In model II (48K) Sorcerers, the cassette interface is on the motherboard, so the Teensy must connect directly to the UART:

    Remove the power supply daughterboard. Remove the UART IC from its...
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    Wiring diagram for early (32K) Sorcerers: ...

    Wiring diagram for early (32K) Sorcerers:

    Remove cassette interface daughterboard and connect Teensy as shown:

    18066
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    Thanks! At 20833 baud with 2 stop bits, the...

    Thanks!

    At 20833 baud with 2 stop bits, the transfer rate is 1.85K bytes/sec. I don't know what the typical rate was for CP/M machines but the Atari 810 was about 1.0 and the CBM 1541 about 0.5...
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    Cool! What do the other 3 knobs do? What does the...

    Cool! What do the other 3 knobs do? What does the blue circuit board do?
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    I meant to say that CD WAV file loading is less...

    I meant to say that CD WAV file loading is less than reliable. Teensy has proven quite reliable.
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    [queued] Tape Simulator for Exidy Sorcerer

    The Exidy Sorcerer (http://oldcomputers.net/sorcerer.html) is an early personal computer, arriving in 1978 on the heels of the Apple II, TRS-80, and PET. It features a 2 MHz Z80, up to 48K RAM, ROM...
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    Failed to find that post again, but found this...

    Failed to find that post again, but found this one which confirms that const is what matters on Teensy....
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    const is fine for named constants, but what about...

    const is fine for named constants, but what about literal constants? Can't find the post now but thought Paul said they use RAM by default.
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    Thanks, that makes sense. Thought I read here...

    Thanks, that makes sense.

    Thought I read here recently that constants go into RAM too unless you F() them. Shame. Not the case with AVR?
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    Teensy RAM Usage

    Not a bug report probably, but I'm curious about Teensy RAM ("dynamic memory") usage in Teensyduino.

    When I compile the Blink example for the Arduino Mega 2560 under Arduino 1.8.8 and Teensyduino...
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    Do some distributors choose not to include the...

    Do some distributors choose not to include the pinout card?
  27. Nice job on the emulators! Thank you for bring...

    Nice job on the emulators! Thank you for bring the wonderful Ataris to the amazing Teensy.

    Your demo videos could use some improvement, though, especially the sideways one. Perhaps some narration,...
  28. Amen, brother!

    Amen, brother!
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    Wow, Frank B, I also learned 6502 (Atari 400) and...

    Wow, Frank B, I also learned 6502 (Atari 400) and Z80 (ZX81) assemblers, and worked on CDC Cyber, in college! Later, at work, I developed microcontroller systems with Z80, Intel 8048, 8041, 8051, and...
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    Cyber Monday Teensy Sale

    over at Sparkfun. 3.5, 3.6, and some others are 20% off:
    https://www.sparkfun.com/categories/267
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    Yes, so many factors can affect performance. But...

    Yes, so many factors can affect performance. But it appears from kinetis.h that Paul has made some choices based on experience, or testing, or manufacturer specs. Apparently, F_MEM must be an integer...
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    Well, I just discovered that there are links in...

    Well, I just discovered that there are links in that tech spec table! When I click on Bandwidth, I get:



    So the question now becomes: How does that value relate to F_MEM in kinetis.h ? There's...
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    Tech Specs: Bandwidth?

    In the tech specs https://www.pjrc.com/teensy/techspecs.html, what does Bandwidth mean, exactly?

    Is it just Bus Clock (words/sec) * 4 (bytes/word) ? If so, is the 192 MB/s value for T3.5 correct?...
  34. Thread: ARM asm?

    by Citabria
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    Thanks again. I selected the port you mentioned...

    Thanks again. I selected the port you mentioned and it works. The other port was left over from the Arduino Nano I had plugged in before.

    Nice work on the Teensy BTW!
  35. Thread: ARM asm?

    by Citabria
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    Maybe not so painless. I installed Teensyduino...

    Maybe not so painless. I installed Teensyduino 1.16 over Arduino 1.0.5 on Mac OS X 10.6.8 and the Blink sketch works. I can modify it and download and run it but when I try the serial monitor I get...
  36. Thread: ARM asm?

    by Citabria
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    Thanks. I found a tutorial for noobs like me...

    Thanks. I found a tutorial for noobs like me which describes Paul's suggestion:
    http://rcarduino.blogspot.com/2012/09/how-to-view-arduino-assembly.html

    Someday I might try working outside the...
  37. Thread: ARM asm?

    by Citabria
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    In Teensyduino, is there a way to view the...

    In Teensyduino, is there a way to view the assembly code produced by the compiler?
  38. Thread: ARM asm?

    by Citabria
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    Thanks!!!!

    Thanks!!!!
  39. Thread: ARM asm?

    by Citabria
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    I just tried it and it seems to work. I added...

    I just tried it and it seems to work. I added __asm__("ldr r0,[r1]\n\t"); to the Blink example and it compiled.

    Is there documentation somewhere about which registers are OK to modify and how to...
  40. Thread: ARM asm?

    by Citabria
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    ARM asm?

    Hi. First-time poster here.

    Does Teensyduino C support the asm statement to embed ARM code for a Teensy3?

    If not, can C code be written to compile to a very tight loop, say ~5 cycles? Example...
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