I am trying to make the GPIO serial port of a Raspberry Pi 2 with Raspbian Wheezy work with an elevator (to control its movement and check status). But before I even plug it into the elevator, I am testing whether I am sending signals correctly from it. As I was having difficulty, I thought I would first test to see if at least my hardware setup is correct, so I reinstalled Raspbian so that the serial console would be re-enabled. I figure that if I can at least get the serial console up and running, I am not wrong on hardware.
The board I'm using is this one:
I have a too-low reputation to post the link to the board vendor or the instructions I'm following.
I'm connecting TX-to-TX and RX-to-RX like this:
I'm plugging it into a PC serial port directly (I found that using a 3m cable made it return garbage to minicom, so is the power too low or something?).
I'm using minicom over /dev/ttyS0 with 115200 8N1 settings, no hardware or software flow control.
When I turn on the Pi by plugging it in with minicom running, I get the 'T1' LED flashing on the serial adapter card, presumably in time with the boot sequence. By itself, nothing appears on the minicom screen.
During this bootup if I hit a key on minicom, the R3 light turns on, and stays on permanently. However, I see the remaining bootup sequence, and it returns to a login prompt. But I cannot type anything to log in. It responds to no keyboard input at all. I have a feeling it has something to do with the R3 light being on permanently. I am doing something right, because a single keyboard tap works to force the Pi to send or the PC to receive the bootup stuff.
What could I possibly be doing wrong here? Is it a minicom setting or am I using the MAX3232 converter wrong?