Datasheet

Parallel Input/Output
MC9S08GT16A/GT8A Data Sheet, Rev. 1
Freescale Semiconductor 87
76543210
R
PTAD7 PTAD6 PTAD5 PTAD4 PTAD3 PTAD2 PTAD1 PTAD0
W
Reset 00000000
Figure 6-8. Port A Data Register (PTAD)
Table 6-1. PTAD Field Descriptions
Field Description
7:0
PTAD[7:0]
Port A Data Register Bits — For port A pins that are inputs, reads return the logic level on the pin. For port A
pins that are configured as outputs, reads return the last value written to this register.
Writes are latched into all bits of this register. For port A pins that are configured as outputs, the logic level is
driven out the corresponding MCU pin.
Reset forces PTAD to all 0s, but these 0s are not driven out the corresponding pins because reset also configures
all port pins as high-impedance inputs with pullups disabled.
76543210
R
PTAPE7 PTAPE6 PTAPE5 PTAPE4 PTAPE3 PTAPE2 PTAPE1 PTAPE0
W
Reset 00000000
Figure 6-9. Pullup Enable for Port A (PTAPE)
Table 6-2. PTAPE Field Descriptions
Field Description
7:0
PTAPE[7:0]
Pullup Enable for Port A Bits — For port A pins that are inputs, these read/write control bits determine whether
internal pullup devices are enabled provided the corresponding PTADDn is 0. For port A pins that are configured
as outputs, these bits are ignored and the internal pullup devices are disabled. When any of bits 7 through 4 of
port A are enabled as KBI inputs and are configured to detect rising edges/high levels, the pullup enable bits
enable pulldown rather than pullup devices.
0 Internal pullup device disabled.
1 Internal pullup device enabled.