Join us at PCIM Europe [10-12 May]. Get free access to virtual booth with myInfineon registration. Learn more

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

Power Management ICs

Not applicable

Hi all,

  •  For our project we are modifying the reference design of MPPT solar charger (
  • Our plan is to include a UART module to serially transmitt the parameters monitored to an external data logger.
  • The available resources in the current design is not enough to include a UART module, so we have to modify it     
  • Two digital block are needed for UART module   in the current design one digital block is free                                                

Following are the design modification we have in mind.....


1.In the design there are four LEDs used for displaying the current status of the battery. we thought of disabling the LEDs which would free two more digital blocks (which are used as PWM for driving those LEDs)  and take out the LEDS from the board and connect some wires in its and use those pins for serial outputs.(which we feel a bit awkward)


2. There are two pins  ISSP_SCK_1_1(connected to P1_0)  and ISSP_SDATA_1_0(P1_1), we thought of using these pins for the RXD and TXD. Can this pin be multiplexed as ISSP while programming and as RXD and TXD while execution??  is that possible?.. This seems quite decent since we can use the available MOLEX pin out in  the board which is used for programming


3.Another option would be to use the pins used for OCD(on chip debugging) for pins are used. Is it possible to  route the signals from the UART block to these pins?? 


We are uncertain about the feasibilty of the modifications 2 & 3. So we are kindly expecting your suggestions.


Any sort of help would be greatly appreciated.





1 Solution
Level 9
5 likes given 1000 replies posted 750 replies posted
Level 9

If you look at following ap note you will see specific conditions about dual role


of pins to observe in terms of loading, and also confirmation that what you are


trtying to do, dual use of ISSP pins in other functions, is OK.





This page more general -





Regards, Dana.

View solution in original post

8 Replies