Hey, so I've been racking my brain over getting a mikroe483 to load a sketch onto my atmega328p. Everything was setup correctly. Sketches would run on the ATmega just would not upload. In a last ditch effort I read somewhere about switching rx and tx lines. I did that and bam works perfect. Why is this? The only way I can get a sketch to upload is to connect TX to TX and RX to RX. Is this an error in the board wiring or what's going on? I worry about printing up a final board and this not being reliable. Thanks
The correct connections are definitely RX-TX, TX-RX. The reason is that "RX" stands for "receive" and "TX" stands for "transmit", so you want to transmit to the receive pin and receive from the transmit pin. If you need to switch them then it's either a wiring error or maybe the pins on the Mikroe-483 are labeled in a confusing manner.
Yeah so after really looking at the data sheet for the mikroe483 it looks like the Tx pin broken out from the the FTDI chip actually goes to the RX. I'm assuming this is to make for simpler wiring but man this one really had me at a loss for while.
Nice find! That is indeed very confusing, since every other USB to TTL serial adapter I've seen has the pins labeled according to their connection to the USB chip. So when you make an RX-RX, TX-TX connection according to the silkscreen on the Mikro-483, you are really making an RX-TX, TX-RX connection between the USB chip and your ATmega328P.