Technical data

MC68HC912B32 MOTOROLA
MC68HC912B32TS/D 19
3.5 Port Pull-Up, Pull-Down and Reduced Drive
MCU ports can be configured for internal pull-up. To reduce power consumption and RFI, the pin output
drivers can be configured to operate at a reduced drive level. Reduced drive causes a slight increase
in transition time depending on loading and should be used only for ports which have a light loading.
Table 7 summarizes the port pull-up default status and controls.
Table 7 Port Pull-Up, Pull-Down and Reduced Drive Summary
Enable Bit Reduced Drive Control Bit
Port
Name
Resistive
Input Loads
Register
(Address)
Bit Name Reset State
Register
(Address)
Bit Name
Reset
State
Port A Pull-up PUCR ($000C) PUPA Disabled RDRIV ($000D) RDPA Full Drive
Port B Pull-up PUCR ($000C) PUPB Disabled RDRIV ($000D) RDPB Full Drive
Port E:
PE7, PE3,
PE2, PE0
Pull-up PUCR ($000C) PUPE Enabled RDRIV ($000D) RDPE Full Drive
PE1 Pull-up Always Enabled RDRIV ($000D) RDPE Full Drive
PE[6:4] None — RDRIV ($000D) RDPE Full Drive
PE[6:5] Pull-down Enabled During Reset — — —
Port P Pull-up PWCTL ($0054) PUPP Disabled PWCTL ($0054) RDPP Full Drive
Port S Pull-up PURDS ($00DB) PUPS0 Disabled PURDS ($00DB) RDPS0 Full Drive
PS[3:2] Pull-up PURDS ($00DB) PUPS1 Disabled PURDS ($00DB) RDPS1 Full Drive
PS[7:4] Pull-up PURDS ($00DB) PUPS2 Disabled PURDS ($00DB) RDPS2 Full Drive
Port T Pull-up TMSK2 ($008D) PUPT Disabled TMSK2 ($008D) RDPT Full Drive
Port DLC Pull-up DLCSCR ($00FD) DLCPUE Disabled DLCSCR ($00FD) DLCRDV Full Drive
Port AD None — —
BKGD Pull-up — — Enabled — — Full Drive