Hello,
I am working on an IR remote but I have a few questions about the hardware
involved and IR (raw) in general.
My understanding of the UART is this:
o All serial data goes through the UART. There is no way around this since
it is the last step before actually sending the data out through the serial
port.
o The UART will automatically append start, stop and parity bits when
sending and remove them on incoming data. This is invisible to the user and
causes no problems assuming both sender and receiver use UART.
o The data in transit is not the actual bit representation of the data but
is in fact the data plus the UART bits.
â?¢ Does all IR data go through the UART? I assume it does since itâ??s a serial
device but I am not sure.
â?¢ Can I get around the UART either by disabling it or just bypassing it all
together? I do not want it to â??helpâ?? me in any way. I want to send out a
specific byte without any UART bits.
â?¢ If I am receiving an IR code from a remote the data received is not the
actual data sent. This is due to two things: (1) the UART has already handled
the data and removed the bits it thought were start, stop and parity; and (2)
if the UART is waiting for a start bit and one never comes, then the UART
will continue waiting for a start bit and ignore the data it receives.
This is my general conception of how the UART works. I know this is probably
flawed in a few areas but thatâ??s why I am posting here. Please correct me and
share any good resources that would help me get a better understanding of how
IR communications work.
Now, hereâ??re some general IR questions and ones related to the remote. I am
using VITOâ??s Oscilloscope to view the IR code from the remote as well as
viewing any bytes I send.
â?¢ One finding is that if I send 0x0B VITO receives 0xF6
o FIRE BYTE: 0x0B = 00001011 = |____|¯|_|¯¯|
o SENT BYTE: 0xF6 = 11110110 = |¯¯¯¯|_|¯|__|
â?¢ I saw something along these lines in an IrDA doc as well.
Does anyone have any information on creating an IR remote? I know devices
without a CIR LED arenâ??t designed to function as such but I still would like
any input you can provide. However, the first step is understanding the UART
and how the data is handled.
Thank you,
Kyle