Chapter 6 Parallel Input/Output Control
MC9S08QE128 MCU Series Reference Manual, Rev. 2
Freescale Semiconductor
113
sinking greater current. Even though every I/O pin can be selected as high drive, the user must ensure that
the total current source and sink limits for the MCU are not exceeded. Drive strength selection is intended
to affect the DC behavior of I/O pins. However, the AC behavior is also affected. High drive allows a pin
to drive a greater load with the same switching speed as a low drive enabled pin into a smaller load.
Because of this, the EMC emissions may be affected by enabling pins as high drive.
6.3
Port Data Set, Clear and Toggle Data Registers
The Port Data Set, Clear and Toggle registers provide an alternate method for setting and clearing
individual port I/O pins within a single port. Only port C and port E have data set, clear and toggle registers.
should be contrasted with
to see the effects of adding Set/Clear/Toggle functionality
to the port cell. SET_Enable, CLR_Enable, and Toggle_Enable will be set to 1 when the user writes to the
Data Set, Clear or Toggle register, respectively. The bit pattern on the peripheral bus port is then used to
perform the requested function on the port data register.
Figure 6-2. Parallel I/O Block Diagram Equipped with SET/CLR Functionality: Ports C & E
Q
D
Q
D
1
0
Port Read
PT
x
DD
n
PT
x
D
n
Output Enable
Output Data
Input Data
Synchronizer
Data
BUSCLK
DATA
SET_Enable
CLR_Enable
Module_Enable
TOGGLE_Enable
Содержание MC9S08QE128
Страница 2: ......
Страница 4: ......
Страница 49: ...Chapter 3 Modes of Operation MC9S08QE128 MCU Series Reference Manual Rev 2 50 Freescale Semiconductor ...
Страница 138: ...Chapter 6 Parallel Input Output Control MC9S08QE128 MCU Series Reference Manual Rev 2 138 Freescale Semiconductor ...
Страница 144: ...Chapter 7 Keyboard Interrupt S08KBIV2 MC9S08QE128 MCU Series Reference Manual Rev 2 144 Freescale Semiconductor ...
Страница 166: ...Chapter 8 Central Processor Unit S08CPUV4 MC9S08QE128 MCU Series Reference Manual Rev 2 166 Freescale Semiconductor ...
Страница 174: ...MC9S08QE128 MCU Series Reference Manual Rev 2 174 Freescale Semiconductor Analog Comparator S08ACMPV3 ...
Страница 202: ...12 bit Analog to Digital Converter S08ADCV1 MC9S08QE128 MCU Series Reference Manual Rev 2 202 Freescale Semiconductor ...
Страница 282: ...Serial Peripheral Interface S08SPIV3 MC9S08QE128 MCU Series Reference Manual Rev 2 282 Freescale Semiconductor ...
Страница 306: ...Timer PWM Module S08TPMV3 MC9S08QE128 MCU Series Reference Manual Rev 2 306 Freescale Semiconductor ...
Страница 320: ...Development Support MC9S08QE128 MCU Series Reference Manual Rev 2 320 Freescale Semiconductor ...