Comments (4)
An easy solution to the r16/r17 usage would be to always use r23 & r24, not just for the t10.
https://github.com/cpldcpu/u-wire/blob/master/firmware/usbdrv/usbdrvasm.S#L23
from u-wire.
Indeed, that looks like an oversight. I am not sure about the impact though, because even if the first test falls through, the loop can still synchronize with the remainder of SYNC. It's only critical if the invocation of the handler is delayed so that there are only 2 sync cycles left.
Regarding the registers: Yes, certainly.
from u-wire.
Good point about having 3 JK transitions to sync to. You've obviously kept your v-usb knowledge fresh despite writing u-wire 6 years ago.
While we are on the topic of the sync, did you notice the rjmp waitForK is odd-cycle aligned?
https://github.com/cpldcpu/u-wire/blob/master/firmware/usbdrv/usbdrvasm12.inc#L87
And with the 16.5Mhz version, where there is an odd number of cycles (11) per bit, the rjmp is even-cycle aligned.
https://github.com/micronucleus/micronucleus/blob/master/firmware/usbdrv/usbdrvasm165.inc#L96
Each waitForK pass is accurate to within 2 cycles, so 2 passes shifted 1 cycle will make the timing accurate within 1 cycle. For the 16Mhz version at 10 2/3 cycles per bit. it should be accurate to within 2/3rds of a cycle, compensating for the 1/3rd cycle jitter in the bit sampling window of the code that follows.
from u-wire.
Well, I spent enough time debugging PHY-level issues with V-USB :) It's a fickle system.
I have not looked into the receiver loops in detail, but I recall that the 16.5 Mhz one was the most stable one. That's is probably the reason why.
Regarding registers in u-Wire: Keep in mind that the tinyavr core (ATtiny10) only has 16 registers. Therefore AVR-GCC uses a different register mapping than on normal AVR and a lot of registers in V-USB had to be moved around to avoid issues.
from u-wire.
Related Issues (3)
- Recieving instead of Sending HOT 1
- Win7 x64 problems HOT 5
Recommend Projects
-
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
-
Vue.js
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
-
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
-
TensorFlow
An Open Source Machine Learning Framework for Everyone
-
Django
The Web framework for perfectionists with deadlines.
-
Laravel
A PHP framework for web artisans
-
D3
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
-
Recommend Topics
-
javascript
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
-
web
Some thing interesting about web. New door for the world.
-
server
A server is a program made to process requests and deliver data to clients.
-
Machine learning
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
-
Visualization
Some thing interesting about visualization, use data art
-
Game
Some thing interesting about game, make everyone happy.
Recommend Org
-
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
-
Microsoft
Open source projects and samples from Microsoft.
-
Google
Google ❤️ Open Source for everyone.
-
Alibaba
Alibaba Open Source for everyone
-
D3
Data-Driven Documents codes.
-
Tencent
China tencent open source team.
from u-wire.