Using pin P5.7 in USIC submodule on XMC4700 chip

[arp4022]

Hi
We are using XMC4700 with LQFP-100 chip format. Our board had tree uarts where one them must use hw controlled flow control becuse paired unit has high priority interrupt that disturbs its UART RX interrupt. Our plan is to use the CTS signal to hold back the transmission of the XMC until the receiver is free to receive more data. Our XMC uses following pins this UART
RX  P5.1
TX  P5.0
CTS P5.7
RTS P5.2
My question is. Is it possible to use P5.7 as CTS because I can not find this pin defined inside the file xmc4_usic_map.h?
#if (UC_DEVICE == XMC4700) && (UC_PACKAGE == LQFP100)

Thanks in advance
Stefan

[arp4022]

Hi again

I found in the reference manual that "Data Inputs (DX4)" has a input to P5.7 namely USIC2_CH0.HWIN2. I will test and see.

[arp4022]

In section 18.2.3.1, inorder to use P5.7 (USIC2_CH0.HWIN2) you must enable CCR.HPCEN to 0x3. To enable HWIN on DX4. Is this neccessary to use HW flow control on a uart? Because in the description of HPCEN it says:

"The hardware port control feature is useful only
for SSC protocols in half-duplex configurations,
such as dual- and quad-SSC. For all other
protocols HPCEN must always be written with
00B."

[Aashita_R · Accepted solution]

Hi @arp4022 ,

Here is the way you can implement CTS and RTS for UART i.e. ASC which you can try on your end -

For CTS implementation, you can use DX2 for hardware trigger as shown in this image taken from the XMC 4700 reference manual-

For RTS implementation, we need to use GPIO to act as RTS and a software workaround solution.

1. Configure RTS as GPIO Output
2. Software prepare UART for receiving mode
3. Software output HIGH to indicate ready to send

Please follow above and check at your end and also, let us know in case of any further query!

Best Regards,

Aashita