Serial communcation with USB to serial(DB9) cable

[rahulsharma]

Hi,
I am using Rockpro64 with Ubuntu18 image.
I have successfully done UART communication of rockpro through ttyS2 port(GPIO6,8) with my laptop.
No i have USB to serial(DB9) cable and i wanted to use one of the USB port of rockpro. I did try the same with 1500000 Baudrate but on my receiver side, i can see a garbage data is coming. I have tried different buadrates too but only garbage data is there.
Any suggestion? Can i use USB port for my serial communication?
Thanks.

[martinayotte]

No i have USB to serial(DB9) cable

I hope you are aware that DB9 are not TTL voltage level, so don't plug it directly to any GPIOs without converter ...

[rahulsharma]

Hi,
Thanks for the suggestion.
I have told that i am using USB to Serial cable. I am not using any GPIO now.

"https://www.amazon.in/Sheen-SOUTSRS-Serial-RS232-Cable/dp/B00JWRW9JM?tag=googinhydr18418-21&tag=googinkenshoo-21&ascsubtag=_k_Cj0KCQiAgf3gBRDtARIsABgdL3lh7afD1kyN3xp4s-RWyzBA_tt5D1_7Xx-Iikuasa_nvg95YW2VwGoaAgwEEALw_wcB_k_&gclid=Cj0KCQiAgf3gBRDtARIsABgdL3lh7afD1kyN3xp4s-RWyzBA_tt5D1_7Xx-Iikuasa_nvg95YW2VwGoaAgwEEALw_wcB"

it is connected through one of USB port. And also been detected as USB0 on rockpro side.
So my question was regarding that only. Can i send data through this cable with 1500000 buadrate?

[martinayotte]

Hi,
Thanks for the suggestion.
I have told that i am using USB to Serial cable. I am not using any GPIO now.

"https://www.amazon.in/Sheen-SOUTSRS-Serial-RS232-Cable/dp/B00JWRW9JM?tag=googinhydr18418-21&tag=googinkenshoo-21&ascsubtag=_k_Cj0KCQiAgf3gBRDtARIsABgdL3lh7afD1kyN3xp4s-RWyzBA_tt5D1_7Xx-Iikuasa_nvg95YW2VwGoaAgwEEALw_wcB_k_&gclid=Cj0KCQiAgf3gBRDtARIsABgdL3lh7afD1kyN3xp4s-RWyzBA_tt5D1_7Xx-Iikuasa_nvg95YW2VwGoaAgwEEALw_wcB"

it is connected through one of USB port. And also been detected as USB0 on rockpro side.
So my question was regarding that only. Can i send data through this cable with 1500000 buadrate?

That is what I mean ... The adapter you are showing is RS232 level ...
What device do you wish to plug on DB9 side ? Is it really a RS232 device ?

Otherwise, you maybe need USB-TTL Serial (not RS232) such as : https://www.amazon.in/SunRobotics-Conver...ef=sr_1_14

[mknawabi]

Hi rahulsharma,

I think you are trying to get serial console access to the rockpro64 by plugging in a USB serial adapter in one of the USB ports. Unfortunately, to get serial access to the RP64, you need a 3V3 TTL serial adapter (FT232 or others) that plug into the GPIO pins.

The guide to get this working is here:
https://forum.pine64.org/showthread.php?...&pid=43567

[rahulsharma]

Hi rahulsharma,

I think you are trying to get serial console access to the rockpro64 by plugging in a USB serial adapter in one of the USB ports. Unfortunately, to get serial access to the RP64, you need a 3V3 TTL serial adapter (FT232 or others) that plug into the GPIO pins.

The guide to get this working is here:
https://forum.pine64.org/showthread.php?...&pid=43567

Hi, 
So that means i can't use usb port for serial communication?
As i have done serial communication with gpio pins (6,8,10) and used a usb to TTL converter. That is done. 
What i asked to use USB port to send serial data for serial communication. Can i do that?

---

@martinayotte

Yes, The device at the receiving end is a serial +-12v. So please suggest how to achieve that.
And anyhow i have to use a TTL to serial converter in between but i want to distinguish two possibilities-
1) one is i use gpio pins(6,8,10) and then use converter
2) If i want to use one of the USB port instead of GPIOs so how can i do that?
Thanks.

[martinayotte]

@rahulsharma, if your end device is really RS232 +/-12V, then, the USB-RS232 adaptor you provide link above will work.