The RKP28sb is a USB development board for the PIC18F2550 or equivalent.

!MCLR VPP RE3            1-----28 RB7 KBI3 PGD
RA0 AN0                  2     27 RB6 KBI2 PGC
RA1 AN1                  3     26 RB5 KBI1 PGM
RA2 AN2 VREF- CVREF      4     25 RB4 KBI0 AN11
RA3 AN3 VREF+            5     24 RB3 AN9  CCP2 VPO
RA4 T0CKI C1OUT RCV      6     23 RB2 AN8  INT2 VMO
RA5 AN4 !SS HLVDIN C2OUT 7     22 RB1 AN10 INT1 SCK SCL
VSS GND                  8     21 RB0 AN12 INT0 FLT0 SDI SDA
OSC1 CLKI                9     20 VDD VPIC
OSC2 CLKO RA6            10    19 VSS GND
RC0 T1OSO T13CKI         11    18 RC7 RX DT SDO
RC1 T1OSI CCP2 !UOE      12    17 RC6 TX CK
RC2 CCP1                 13    16 RC5 D+ VP
VUSB                     14----15 RC4 D- VM

J9 ICSP         PIC18F2550              J6              PIC18F2550
-------         ----------              --------------  ----------
1:VPP           !MCLR VPP RE3           10:RB1/SCL/SCK  RB1 AN10 INT1 SCK SCL
2:VDD/VPIC      VDD/VPIC                 9:RB0/SDA/SDI  RB0 AN12 INT0 FLT0 SDI SDA
3:VSS/GND       VSS/GND                  8:RA3/VREF     RA3 AN3 VREF+
4:PGD           RB7 KBI3 PGD             7:GND          GND
5:PGC           RB6 KDI2 PGC             6:RB1/SCL/SCK  RB1 AN10 INT1 SCK SCL
6:NC                                     5:RC7/RXD/SDO  RC7 RX DT SDO
                                         4:RB0/SDA/SDI  RB0 AN12 INT0 FLT0 SDI SDA
J5 POWER                                 3:RA5/TXD/SS   RA5 AN4 !SS HLVDIN C2OUT
--------                                 2:RC1          RC1 T1OSI CCP2 !UOE
1:RST           !MCLR VPP RE3            1:RC0          RC0 T1OSO T13CKI
2:3V3           +3V3
3:5V            +5V             J8       J4
4:GND           GND             ---      -----
5:GND           GND             SCK      8:RB7          RB7 KBI3 PGD
6:VIN           VIN             VUSB     7:RB6          RB6 KBI2 PGC
                                3V3      6:RB5          RB5 KBI1 PGM
J3 ANALOGUE                              5:RC2          RC2 CCP1
-----------                              4:RC4/D-       RC4 D- VM
1:RA0/AN0       RA0 AN0                  3:RC5/D+       RC5 D+ VP
2:RA1/AN1       RA1 AN1                  2:RC6/TXD      RC6 TX CK
3:RA2/AN2       RA2 AN2  VREF- CVREF     1:RC7/RXD/SDO  RC7 RX DT SDO
4:RB2/AN3       RB2 AN8  INT2  VMO
5:RB3/AN4       RB3 AN9  CCP2  VPO
6:RB4/AN5       RB4 KBI0 AN11

Power may be applied through the power jack or the power header. There are two LDOs and a jumper is used to select the MCU voltage between 3V3 or 5V. When applying 5V on the power header, the 3V3 LDO is still utilised so it may be selected.

When using the power jack socket, the switch will turn the board on and off, as it feeds the 5V LDO.

There is a VUSB selection jumper which may power this pin if the PIC internal regulator is disabled. For PICs that are not USB, remove the jumper and use this a method of accessing pin 14.

Constructors guide
Schematic