I've bought a small Max3232 module to attach to a Rasp Pi 3 B. I want to use it to control a RoboFocus which uses a serial (DB9) cable to the PC side. I'veone a bit of hacking at the Pi case to fit the module in. But I've halted there while I decide how to connect it to the GPIO. The module outputs are VCC, TX, RX and Gnd. The module is also described as being 3.3V/5V. But I'm not sure how to read that. Does it mean it wants a 3.3V input from the GPIO side which it converts to 5V to talk to my external device (e.g. RoboFocus). Or does it want 5V?
I question it because in this article, the writer says, and shows by photos, that the 5 volt pinout is the one to use, not 3.3 volt.
http://www.davidhunt.ie/add-a-9-pin-...in-10-minutes/
And the next question is about the 3.3VDC GPIO pin. The newer 40-pin GPIOs seem to have 2 x 3.3V pins whereas the older 26 pin version only had 1 and that one only had enough power to run a LED or two. The later versions have a lot more I believe. But I hope someone with more Pi knowledge than me can confirm this.
It's an issue for me because I have also installed a real-time clock board which is using the 3.3VDC at Pin 1. So I will have to use the Pin 17 if it is in fact that's the voltage the 323 module needs. If it's 5 volts it needs, then it isn't a problem because that voltage can be picked up at several points.
Then and finally, a question about the configuration of the module to work with external serial devices. I understand the native setup uses the serial connection for a console and that this needs to be disabled first by editing the /boot/cmdline.txt file to delete references to TTYAMA0 and also editing /etc/inittab in a similar way.
Peter
