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Grorel's avatar
Grorel
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7 years ago

Can the Cyclone V SoC UART Controller be used as RS485 ?

I have a Cyclone V SoC running in my product with Linux on the ARM. I uses UART0 controller on the HPS pins for the linux console mounted on /dev/ttyS0. The UART1 controller signals are linked to t...
JOHI's avatar
JOHI
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7 years ago

Hello,

What you are experiencing is a typical RS485 problem: If your slave device is too fast, you need a specific driver that changes a Max485 or similar tranceiver from lo to high impedance (write to read). The 16550 uart has a TEMT (transmitter empty interrupt), this interrupt can be used to toggle the direction of the bus driver when direction of data needs to change (just after all bits have left the uart).

The Nios 16550 source code can be modified to do what you need, what the possibilities with the Linux driver are, I cannot tell.

Best Regards,

Johi.