LowLevel RS232
JerryE
Posts: 5
Hi all again.
·
I will try to explain this better. I am checking the Rs232 with a normal 100mhz oscilloscope.
With this I see the startbit, 8 databits and the stop bit exactly as it comes out from my pc.
(no TTL, both timing and levels) When I using a terminal· (almost anyone works fine)
in my pc I can send any byte by holding the alt key and then put the value in decimal 1-255.
(need to always be 3 letters, ex, 001,064,255 etc) When I do this I can easily understand
the number 1-126 on my oscilloscope, this is showing normal binary pattern but when the
numbers go to 127 and above it is not· as clear anymore. When I send 126 the binary
I see on my oscilloscope is 01111110 and this is 126 but when I send 127 it is 10100110
and this is 166. I can not really understand this??? Anyone who can explain this??
I doing this because I going to implement lowlevel coding in the Sx28 to receive and send
data to other units. To build up the protocol I need to understand this facts so I can working
with real bytes. Regard Jerry
·
I will try to explain this better. I am checking the Rs232 with a normal 100mhz oscilloscope.
With this I see the startbit, 8 databits and the stop bit exactly as it comes out from my pc.
(no TTL, both timing and levels) When I using a terminal· (almost anyone works fine)
in my pc I can send any byte by holding the alt key and then put the value in decimal 1-255.
(need to always be 3 letters, ex, 001,064,255 etc) When I do this I can easily understand
the number 1-126 on my oscilloscope, this is showing normal binary pattern but when the
numbers go to 127 and above it is not· as clear anymore. When I send 126 the binary
I see on my oscilloscope is 01111110 and this is 126 but when I send 127 it is 10100110
and this is 166. I can not really understand this??? Anyone who can explain this??
I doing this because I going to implement lowlevel coding in the Sx28 to receive and send
data to other units. To build up the protocol I need to understand this facts so I can working
with real bytes. Regard Jerry
Comments
[noparse][[/noparse] The order is: start bit, data bits (LSB first, MSB last), parity (if used), stop bit. ]
Post Edited (PJ Allen) : 7/15/2006 1:53:09 PM GMT
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
realterm.sourceforge.net/[noparse][[/noparse]url]
It has specific options to send binary versus ASCII data, as well as different options to display the incoming data, etc, etc. A really powerful terminal program, complete with source code for those who want it.
Thanks, PeterM