Olimex Support Forum

Others => UEXT => Topic started by: JeanFrancois on January 04, 2022, 06:53:20 pm

Title: Module RS-485 half duplex with external RTS support
Post by: JeanFrancois on January 04, 2022, 06:53:20 pm
Good day,

Using the module in pass mode under half duplex requires the use of an external RTS signal.

How can we use the device in half duplex ? It's not possible to use i2c to turn on/off driver enable due to latency.

I have worked around by modifying the firmware so as to use one of the pins exported to ICSP as an input driven by external RTS from the master.

Can Olimex designer please clarify on this matter ?

Thank you

Jean-Fran├žois
Title: Re: Module RS-485 half duplex with external RTS support
Post by: lambda on January 12, 2022, 01:32:12 pm
It seems you are actually using MOD-RS485-ISO.

Instead I would use MOD-RS485 https://www.olimex.com/Products/Modules/Interface/MOD-RS485/open-source-hardware which is cheaper and does exactly what you seem to want.
Title: Re: Module RS-485 half duplex with external RTS support
Post by: JeanFrancois on January 13, 2022, 01:37:35 am
Hi Lambda,

Yes indeed, thanks for spotting that.

For that project, I knew only on client hardware delivery I needed half duplex and to I tweaked the ISO one, but will be definitely better with this one in the future, i'll look into the wiring details;

Thx and regards

Jean-Fran├žois