MCU to FTDI / RS232

Thread Starter

Wolframore

Joined Jan 21, 2019
2,243
I have a project to design a converter with data gathered with a MCU to output through USB or RS232. I’m using a MAX232 and an FTDI chip. The chips are connected to the TX/RX of the MCU. Only one will be used at one time. USB 5V will be utilized in both situations.
Is there a best way to jumper or select between USB to RS-232? I’ve thought about removing ground or power to the respective chip but wonder if data streams may power the chips. The chips do not have enable Pins
 

MrChips

Joined Oct 2, 2009
23,054
It is not clear what is your situation.

Device #1 <--> Device #2

What is on Device #1, USB, TTL, RS-232?
What is on Device #2. USB, TTL, RS-232?
 
I have a project to design a converter with data gathered with a MCU to output through USB or RS232. I’m using a MAX232 and an FTDI chip. The chips are connected to the TX/RX of the MCU. Only one will be used at one time. USB 5V will be utilized in both situations.
Is there a best way to jumper or select between USB to RS-232? I’ve thought about removing ground or power to the respective chip but wonder if data streams may power the chips. The chips do not have enable Pins
of course the chips have enable pins- Vcc. Just ground their Vcc pin to turn the chip _OFF_ . You can control this with a transistor.
 

Thread Starter

Wolframore

Joined Jan 21, 2019
2,243
this is what I came up with... might be a better way but it appears to works. 3 pin header with a jumper for power in center pin

1617912636924.png
edit: the gates should get pull downs
 
Last edited:

Thread Starter

Wolframore

Joined Jan 21, 2019
2,243
It is not clear what is your situation.

Device #1 <--> Device #2

What is on Device #1, USB, TTL, RS-232?
What is on Device #2. USB, TTL, RS-232?
MCU decodes input data and transmits via TTL UART so it can be transmitter by either:

1. USB

OR

2. RS232

that’s about as far as it was explained to me at the moment
 
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