Forum: Mikrocontroller und Digitale Elektronik Remappable pin selection for PIC18F66J94


von Ari123 L. (Firma: Kynix Semiconductor HongKong L) (yumi1)


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Hi all,
I am new to this series of controller but earlier i had worked with 
PIC24FJ256GB406.
In PIC24FJ256GB406 controller(see datasheet at 
http://www.kynix.com/Parts/158737/PIC24FJ256GB406-I%2FPT.html), any 
remappable pin can be configured for any type of peripheral feature for 
example we can map uart3RX on any of the remappable pin. There is no 
restriction to which remappable pin uart3rx has been connected. Based on 
this only i had designed my new design for PIC18F66J94 controller and 
got PCB fabricated also but i think i have done blunder in configuring 
the remappable pins.
For PIC18F66J94 controller, remappable pins have been grouped together 
and divided into different groups i.e. for using U3RX any one of these 
remappable pins can only be used i.e. 
RP0,RP4,RP8,RP12,RP16,RP20RP24,RP28,RP32,RP36,RP40 and RP44.
I didn't care for this grouping while designing the schematic.
Now i need to configure 3 uart lines through remappable pins as follows
RP3->RX,RP2->TX,RP1->RX,RP0->TX,RP18->TX,RP19->RX. I can't change the RX 
and TX lines on the slave device as they are non-remappable.
Out of these 3 i can configure only one set of uart line i.e. RP3 as 
U1RX and RP2 as U1TX. I want to know if there is any other possibility 
without changing the hardware connection?
Regards

von Dieter W. (dds5)


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There is no way to get around the limitation caused by that mapping 
scheme.

The reason why Microchip calls it "PPS-Lite" is the restriction to only 
4 bits to select a distinct remappable pin (in contrast to PIC24).

As a result you can only choose from 16 different pins out of a total 
amount of 45 remappable pins available on that controller.
Splitting these 45 pins into 4 groups will cut the number down to less 
than 16 per group.

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