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October 5, 2009
about 3 years ago
Figured it out ... The UART TXD should actually go to RX-I and UART RXD to TX-O. Seems odd that this should be the case, but now that comment somewhere below about the TX-O/RX-I pins being swapped on the SP3485 makes sense ... Hope this helps someone.
I have two of these wired up to UARTs 4 & 5 on a Beaglebone Black. The UARTs are properly (and tested!) muxed in the overlay. So I have TXD, RXD and RTS connected to the equivalent pins on the BOB-10124's (TX-O, RX-I and RTS pins) along with the requisite +3.3V and GND.
The BOB-10124's are connected with about a foot of CAT5 cable, A-A, B-B and GND to GND. My application code is pretty simple.
For both UARTs, I open /dev/ttyO4/5 and set up the speed etc. (no RTS/CTS):
UART4: Simply reads from the UART, prints out what it gets
UART5: 1) RTS enabled with ioctl(TIOCMBIS) on bit TIOCM_RTS 2) Delay 25ms 3) Write message 4) Delay 100ms 5) RTS disabled with ioctl(TIOCMBIC) on bit TIOCM_RTS
However, I cannot get it to transfer anything (or at least the receiving module (UART4) doesn't receive anything). I do see the RTS LED go on, then off after a brief pause, so it looks like it's sending. I know the pins and UART config is correct because if I just cross the UART pins directly it works fine.
I've tried many combinations, enabling RTS/CTS in the ioctl(TCSETS) initial set up ... so far nothing has worked.
I have a Saleae Logic, but it's an old one and doesn't do RS-485 (it's limited to 0-5v and doesn't have any analog channels), maybe this is an excuse to buy a Logic-8 ...
about 3 years ago
Love this product, used it extensively for 2 years. However, it just started acting up, it won't power off properly. I switched it off and nothing happened; in normal use, it'll stay on for a long enough to cool so it can shut the air down safely, but for whatever reason now it just keeps heating. Ended up having to unplug, plug back in (still didn't fix the issue), then set the temp to 100, then pull the plug when it hit 100. Weird. Anyone else seen this?
No public wish lists :(