Wednesday, July 10

Geek

Daily News Stuff 10 July 2019

Fuck I Did It Again Edition

Tech News

  • I was looking for the best option to add sound to my design for an 8/32-bit computer.  My restrictions are that whatever I use for the job has to be cheap - certainly less than A$10; readily available; and hobbyist friendly.  I need something that can drop into a breadboard, or at worst drop into a socket that can drop into a breadboard.  That means either a DIP or PLCC part.

    The usual way to deliver audio these days is to attach a codec to a high-speed serial port such as I2C or SPI, both of which I have available.  Out of more than seven hundred codec chips available, how many support one of those interfaces and come in DIP or PLCC?

    Zero.  Not a single one.

    It turns out that if you want to add audio to a PIC in a hobbyist-friendly way, the simplest - no, the only practical approach - is to use another PIC.

    The PIC16F177x range includes up to four DACs, but you have to be careful because two of them will only be 5 bits and not terribly useful for audio, but one or two will be ten bits.  By comparison, the original Amiga had 8-bit DACs and didn't sound completely terrible.  PIC16 is an 8-bit part (despite the name) but runs at 32MHz so it's quite capable of handling simple audio generation.

    PIC24 is a 16-bit range (despite the name) and also offers internal DACs, but I can't find any parts in a DIP package with DACs.  It's possible they're just hiding, but there is a better alternative.

    And that's the dsPIC33FJ128GP802-I/SP.  It's a 16-bit part too - yeah, Microchip are not good at this - running at 40MHz.  It has up to 128KB flash and 16KB RAM, dual 16-bit DACs (or really, dual 14-bit DACs that take 16-bit input).

    The CPU has DSP enhancements including separate X and Y memory and buses so that it can read two data values per clock cycle, and a single-cycle multiply/accumulate with 40 bit output, saturation and rounding control, and fractional values (though not true floating point).

    And it all comes in a 28-pin narrow DIP just like the PIC32MX270F256B-50I/SP I hope to use as my CPU and GPU.  Cost is actually slightly higher - A$8.19 vs. A$6.65, both qty 1 - which I put down to the DACs.

  • I found a source for RAMDACs.  PLCC-44, which is acceptable.  256x24 lookup table, so 16,777,216 colours instead of 64.  US$3.17.  It's an old Brooktree chip, so it requires a 5V power supply an a 1.2V reference, which is annoying.  They claim to have 152,000 of them in stock, which I guess is possible considering these used to be on every graphics card in the world and the remaining parts had to end up somewhere.

  • Any law you can pass I can pass worser.  I can pass any law worser than you.

    No you can't.

    Yes I can.

    No you can't.

    Yes I can.

    No you can't.

    Oui je peux! Oui je peux!  (TechDirt)

  • Looking for an underpowered laptop with a good screen?  Now's your chance!  (NotebookCheck)

    That said, this is rather Chuwi's stock in trade - they previously had a Microsoft Surface clone with a beautiful 3000x2000 display - and a cheap Atom CPU.

  • Facebook's updated community standards permit users to post death threats but only if they're really annoyed about something.  (One Angry Gamer)

  • Meanwhile Twitter will ban you if you say mean things.  (Twitter)

    Why do these idiots get this wrong every single time?

    Oh.  Answered my own question there.

  • A gigabit of flash costs the same as a megabit of SRAM.  (Mouser.com)

    The flash is also faster.  Well, for sequential reads anyway.

Disclaimer: Buggrit.  Buggrem.  Millennial hand and shrimp.

Posted by: Pixy Misa at 08:04 PM | Comments (4) | Add Comment | Trackbacks (Suck)
Post contains 639 words, total size 5 kb.

1 24-pin BGA with 16 NC pins?  Nice.

Posted by: Rick C at Thursday, July 11 2019 03:04 AM (Iwkd4)

2 I'm almost positive now my motherboard suffered damage when my water pump died, because the thing would restart when I shut it down.  So off to Micro Center I went today to get...uh...the ONE model X570 they had on the floor (other than the $700 one, which, well, no), the ASUS Pro WS X570-ACE, a workstation motherboard, which means "No RGB, and it has a U.2 socket" as well as dual m.2, 4 SATA 6Gbps and 2 gigabit ethernet, one of which is Intel.
So far it's pretty nice--without any adjustments, the CPU's running closer to the boost clock (CAM says it's at 4350MHz) and a hair cooler (I didn't get a new case so it's on my desk, open air style for now; that probably doesn't help)
You can't hear the chipset fan even though it's running at 2700RPM.

Posted by: Rick C at Thursday, July 11 2019 12:26 PM (Iwkd4)

3 That looks like a pretty nice board.

Posted by: Pixy Misa at Thursday, July 11 2019 02:32 PM (PiXy!)

4 Yep.  Sadly, a lot of it will go unused, which is mainly why I'd been previously using mini ITX.
It came with a coupon for a 20% discount on an order from cablemod, too smile

Posted by: Rick C at Friday, July 12 2019 02:56 AM (Iwkd4)

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Apple pies are delicious. But never mind apple pies. What colour is a green orange?




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