WIZnet Developer Forum

WIZ107SR lost data! From QnA

Hi hkjung,

Back in Sept. 2013 this question was ask by javakys, and never got a replay.

For months our products have had NO use for hardware flow control ie RTS/CTR, and systems is running fine with

In our current & new design there is a NEED to implement flow control, and as it turns out the [color=#0000FF]RTS[/color] pin on the
WIZ107SR TTL is held permanently LOW, except when you momentarily drive the nRESET pin, will the [color=#0000FF]RTS[/color] pin toggle
to HIGH for 440ms.

No toggling on the [color=#0000FF]RTS[/color] pin when there is incoming data from E2U interface?
As you are aware, WIZ107SR will only pass data from E2U only when [color=#0000FF]CTS[/color] pin is held low.
As you are aware, WIZ107SR will never signal on the [color=#0000FF]RTS [/color]pin that E2U data is in buffer ready for UART interface.

Is this how WIZNET has implemented flow control on the WIZ107SR?
1. That ONLY [color=#0000FF]CTS[/color] pin is what the module monitors?
2. That when WIZ107SR is turned ON, [color=#0000FF]RTS [/color]pin is always held LOW to indicate E2U data ready?

We had carried extensive test on these modules and all 20+ units exhibit above characteristics.

Module WIZ107SR,
PCB release 1.1,
Firmware 2.20.


Hello Hanspeter,

I saw what you explained in details.
However, I can say that WIZ107SR supports CTS/RTS flow control on itself.

By the way, the HW revision of module and FW version is too old.
I recommend you use new HW and latest firmware instead of what you have on your hand.
The current HW revision number is Rev1.4 and the latest firmware version is 4.05

The mechanism of handling serial data buffer was updated continuously and I believe you will not see data loss any more.
Unfortunately, FW 4.05 can operate on HW rev 1.3 and rev 1.4 but it will not run on HW rev 1.1
You’d better buy new one with Rev 1.4

Thank you.


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