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8 Universal Port Multiplexer (UPMUX)
8.1 Overview
UPMUX is a multiplexer that allows software to assign the desired peripheral I/O function to an I/O port. The main
features are outlined below.
• Allows programmable assignment of the I
eral I/O functions to the P0, P1, P2, and P3 port groups.
• The peripheral I/O function assigned via UPMUX is enabled by setting the PPORTPxFNCSEL.PxyMUX[1:0] bits
to 0x1.
Note: 'x', which is used in the port names Pxy, register names, and bit names, refers to a port group (x
= 0, 1, 2, 3) and 'y' refers to a port number (y = 0, 1, 2, ··· , 7).
Figure 8.1.1 shows the configuration of UPMUX.
UPMUX
PxyPPFNC[2:0]
PxyPERICH[1:0]
PxyPERISEL[2:0]
8.2 Peripheral Circuit I/O Function Assignment
An I/O function of a peripheral circuit supported may be assigned to peripheral I/O function 1 of an I/O port listed
above. The following shows the procedure to assign a peripheral I/O function and enable it in the I/O port:
1. Configure the PPORTPxIOEN register of the I/O port.
- Set the PPORTPxIOEN.PxIENy bit to 0.
- Set the PPORTPxIOEN.PxOENy bit to 0.
2. Set the PPORTPxMODSEL.PxSELy bit of the I/O port to 0.
3. Set the following UPMUXPxMUXn register bits (n = 0 to 3).
- UPMUXPxMUXn.PxyPERISEL[2:0] bits
- UPMUXPxMUXn.PxyPERICH[1:0] bits
- UPMUXPxMUXn.PxyPPFNC[2:0] bits
4. Initialize the peripheral circuit.
5. Set the PPORTPxFNCSEL.PxyMUX[1:0] bits of the I/O port to 0x1.
6. Set the PPORTPxMODSEL.PxSELy bit of the I/O port to 1.
S1C31D50/D51 TECHNICAL MANUAL
(Rev. 2.00)
C, UART, synchronous serial interface, and 16-bit PWM timer periph-
2
Input data
selector
Output data
selector
Figure 8.1.1 UPMUX Configuration
Seiko Epson Corporation
8 UNIVERSAL PORT MULTIPLEXER (UPMUX)
Data, I/O control
Function 1 selection
(Disable input)
(Disable output)
(Disable peripheral I/O function)
(Select peripheral circuit)
(Select peripheral circuit channel)
(Select function to assign)
(Select peripheral I/O function 1)
(Enable peripheral I/O function)
Peripheral circuit
I/O port
Pxy
8-1
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