Search found 9 matches

by dave j
Sun Nov 26, 2017 3:20 pm
Forum: Code snipplets
Topic: Fast bitbanding gpio/sram access
Replies: 22
Views: 573

Re: Fast bitbanding gpio/sram access

The advantages from bit-banding really come from pre-calculating the address - that way you just need to do a read or write when you use it. Calculating it each time as you are doing loses the main advantage of the technique.
by dave j
Fri Nov 24, 2017 5:12 pm
Forum: Code snipplets
Topic: Dual LFO with choice of waveforms using PT8211 and Blue Pill
Replies: 22
Views: 994

Re: Dual LFO with choice of waveforms using PT8211 and Blue Pill

The output of the PT8211 is going through a 47uF capacitor to a potential divider of two resistors to bring the level down to 1V peak-to-peak before I send it into the LINE IN on the PC. The screen captures are from a PC software oscilloscope, using the Sound Card LINE IN input. Sound card inputs a...
by dave j
Wed Nov 22, 2017 8:37 pm
Forum: General discussion
Topic: Newbie question about 'short' and 'uint16_t' data types
Replies: 10
Views: 283

Re: Newbie question about 'short' and 'uint16_t' data types

The F4 (and F3) use the ARM M4 core which has 16 bit SIMD instructions and so can speed up 16 bit arithmetic. I don't think GCC supports those instruction though so you have to use them via intrinsics or assembler. That doens't help you though because the F1's M3 core doesn't have them. In terms of ...
by dave j
Thu Nov 16, 2017 10:16 pm
Forum: New users MUST post here first, and let us know a bit about you and your projects
Topic: Decoding the Gameboy LCD output.
Replies: 123
Views: 1691

Re: Decoding the Gameboy LCD output.

And well the STM32 can get the data kinda fine, but it's the transfer part in real time that's problematic cause of the slow USB Serial. It's worth keeping in mind that the arduino libraries add layers on top of the hardware. In the case of USB, STM32F1s have a 512 byte buffer that they have to use...
by dave j
Tue Nov 14, 2017 5:43 pm
Forum: New users MUST post here first, and let us know a bit about you and your projects
Topic: Decoding the Gameboy LCD output.
Replies: 123
Views: 1691

Re: Decoding the Gameboy LCD output.

There's an article Sniff your Game Boy's LCD using a logic analyzer where someone describes capturing GameBoy screen output using a Saleae logic analyzer. It might help you make sure you're capturing things correctly.
by dave j
Mon Nov 06, 2017 4:16 pm
Forum: Off topic
Topic: 100MHz or 200MHz DSO
Replies: 5
Views: 182

Re: 100MHz or 200MHz DSO

Check out the EEVblog forum. Some scopes are hackable - even to increase bandwidth.
by dave j
Fri Nov 03, 2017 12:29 pm
Forum: New users MUST post here first, and let us know a bit about you and your projects
Topic: Hello
Replies: 2
Views: 86

Re: Hello

Welcome dave Glad to have you onboard ;-) Thanks. BTW. F3 is a bit of an odd device. i.e quite specialised and not used as much as the F1 and F4 (though I see its used in some flight control units) Given the interest in DIY oscilloscopes you'd think a chip with 4 fast ADCs, built in opamps and anal...
by dave j
Thu Nov 02, 2017 9:32 pm
Forum: New users MUST post here first, and let us know a bit about you and your projects
Topic: Decoding the Gameboy LCD output.
Replies: 123
Views: 1691

Re: Hi, hobbyist trying things out:P

I'd have thought using a the gameboy's clock to drive a timer which in turn controls DMA reading a port would be the best way to go. DMA channels can be configured in circular mode, they just loop around and start filling the buffer from the beginning again. They can generate interrupts when the buf...
by dave j
Thu Nov 02, 2017 8:56 pm
Forum: New users MUST post here first, and let us know a bit about you and your projects
Topic: Hello
Replies: 2
Views: 86

Hello

Lots of experience programming professionally, everything from device drivers to web apps, mainly focussed on infrastructure bits. Retired now and decided I'd like to develop my knowledge of electronics. I've done a bit of digital before and would like to also learn some analogue stuff beyond V=IR. ...