PC to MCU Serial communication connector

Thread Starter

Chandler Timm Doloriel

Joined Apr 5, 2018
52
Hi folks,

I have this ADM3202 in my board which is to be used to communicate serially from PC to MCU and vice versa. It's main functions are to send commands from PC-MCU and receive sensor data (fprintf) from MCU-PC only.
ADM3202.PNG
I wonder what external connector should I use to connect it to my PC.
1. DB9 RS-232 Serial to Terminal adapter Connector Breakout Board

RS232.PNG
2. FTDI Serial TTL-232 USB Cable
FTDI Serial TTL-232 USB Cable.PNG

I don't have the actual hardware yet and the board, so there is no way I can test it practically.
If someone can help, thank you very much!

Regards,
Chandler
 

John P

Joined Oct 14, 2008
1,839
Are you really using RS-232 communication? These days, not many computers have it. You're showing pictures of adapters, but one of them is from USB to logic-level UART, and the other is just a breakout board giving you access to the individual wires in a 9-pin RS-232 connector. If you really must use RS-232, then you either need a compatible port on the computer, or a USB adapter like this:
https://www.amazon.com/USB-Serial-Adapter-Modem-9-pin/dp/B008634VJY
 

OBW0549

Joined Mar 2, 2015
3,551
Beware: you absolutely CANNOT use the FTDI TTL-232 to connect to your ADM3202 because their signal levels are not compatible: the FTDI device operates on TTL levels (0-5V or 0-3.3V, depending on the model), while the ADM3202 sends/receives on +/-6V levels.

The method suggested above by @John P is the way to go.
 

Thread Starter

Chandler Timm Doloriel

Joined Apr 5, 2018
52
Are you really using RS-232 communication? These days, not many computers have it. You're showing pictures of adapters, but one of them is from USB to logic-level UART, and the other is just a breakout board giving you access to the individual wires in a 9-pin RS-232 connector. If you really must use RS-232, then you either need a compatible port on the computer, or a USB adapter like this:
https://www.amazon.com/USB-Serial-Adapter-Modem-9-pin/dp/B008634VJY
Thank for this sir. Just for clarification, is this the configuration that i need to set-up to facilitate rs232 communication of pc and mcu?
rs232 comms.PNG
Also, in the schematic it says that ADM3202 have +/-6V signals. Will the configuration above allows or compatible with +/-6V data lines?
 

djsfantasi

Joined Apr 11, 2010
6,834
Thank for this sir. Just for clarification, is this the configuration that i need to set-up to facilitate rs232 communication of pc and mcu?
View attachment 218113
Also, in the schematic it says that ADM3202 have +/-6V signals. Will the configuration above allows or compatible with +/-6V data lines?
I don’t think so. You need a USB to RS232 adapter. The correct answer depends on the interface at both ends. If the PC is USB and the MCU is RS232, then my comments apply.

UPDATE: Missed the detail of the first cable. My error. I agree with John P.
 
Last edited:

John P

Joined Oct 14, 2008
1,839
No, it looks right to me. The first item connected to the computer looks like a USB-to-RS232 adapter, but I think they sometimes come with just logic levels on the 9-pin connector, so I'd check it carefully. But Chandler, can you not bypass that ADM3202? It's stepping up the signals to RS-232 levels (well, actually not the full specification, but +/-6V should work) and then you need more hardware to deal with it. If you could use the logic level signals on pins 11 and 12 of the ADM3202, it would all be simpler.
 
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