Hi there,
I managed to connect an AT keyboard to a 8051µC
At the start of the code I managed to lid the led's one by one and then turn them all off at once. So far so good
Now I'm trying to lid the NumLock led when the NumLock key is pressed.
Eveything works fine but when I look at the signals on the scoop I noticed some strange things.
File NumLock key pressed
0) Data line is first set low by keyboard, then comes the clock.
1) When all data is send the data line remain at a high level.
2) The 520µs Clock low at the end of the zoomed area is due to processing time of received byte.
File NumLock key released
Reveiving bytes 0F0h and 77h from keyboard, data line high at start, 2 times 11 clock pulses and finally processing time by µC while clock driven low by µC
First strange thing:
Why is the data line going low after processing the second byte??? First byte ok but not second one
File NumLock LED On
Three packages:
1) Command 0EDh to keyboard
2) Data for led's
3) ACK from keyboard
Second strange thing
Why is the data line going low BEFORE the falling edge of the clock when sending the data for the led's?
The signals I measure don't match the ones described here: **broken link removed** especially the ones for µC to Keyboard
Do I need to send something more to the keyboard, set/reset the data line myself after receiving data, ... ...?
All suggestions are welcome
I managed to connect an AT keyboard to a 8051µC
At the start of the code I managed to lid the led's one by one and then turn them all off at once. So far so good
Now I'm trying to lid the NumLock led when the NumLock key is pressed.
Eveything works fine but when I look at the signals on the scoop I noticed some strange things.
File NumLock key pressed
0) Data line is first set low by keyboard, then comes the clock.
1) When all data is send the data line remain at a high level.
2) The 520µs Clock low at the end of the zoomed area is due to processing time of received byte.
File NumLock key released
Reveiving bytes 0F0h and 77h from keyboard, data line high at start, 2 times 11 clock pulses and finally processing time by µC while clock driven low by µC
First strange thing:
Why is the data line going low after processing the second byte??? First byte ok but not second one
File NumLock LED On
Three packages:
1) Command 0EDh to keyboard
2) Data for led's
3) ACK from keyboard
Second strange thing
Why is the data line going low BEFORE the falling edge of the clock when sending the data for the led's?
The signals I measure don't match the ones described here: **broken link removed** especially the ones for µC to Keyboard
Do I need to send something more to the keyboard, set/reset the data line myself after receiving data, ... ...?
All suggestions are welcome