
122
Note 4:
The function of P17 or P12 is selected via the P17/P12 select bit in the Ring Filter Select
Register in Logical Device 8 at 0xC6.
The GPIO Data and Configuration Registers are located in Logical Device Block Number
8.
Note 5:
RUN STATE GPIO DATA REGISTER
ACCESS
The GPIO data registers as well as the
Watchdog Timer Control, and the Soft Power
Enable and Status registers can be accessed by
the host when the chip is in the run state if
CR03 Bit[7] = 1. The host uses an Index and
Data port to access these registers (TABLE 51).
The Index and Data port power-on default
addresses are 0xEA and 0xEB respectively. In
the configuration state the Index port address
may be re-programmed to 0xE0, 0xE2, 0xE4 or
0xEA; the Data port address is automatically set
to the Index port address + 1. Upon exiting the
configuration state the new Index and Data port
addresses are used to access the GPIO data,
Soft Power Status and Enable, and the
Watchdog Timer Control registers.
For example, to access the GP1 data register
when in the run state, the host should perform
an I/O Write of 0x01 to the Index port address
(0xEx) to select GP1 and then read or write the
Data port (at Index+1) to access the GP1
register. Generally, to access any GPIO data
register GPx the host should perform an I/O
Write of 0x0x to the Index port address and then
access GPx through the Data port. The Soft
Power and Watchdog Timer Control registers
are accessed similarly.
TABLE 51 - INDEX AND DATA PORTS
PORT
ADDRESS
0xE0, E2, E4, EA
Index address + 1
PORT
NAME
Index
Data
RUN STATE ACCESS
0x01-0x0F
Access to GP1, Watchdog Timer
Control, GP5, GP6, and the Soft
Power Status and Enable
registers (see TABLE 52).
TABLE 52 - RUN STATE ACCESSABLE CONFIGURATION REGISTERS
RUN STATE REGISTER
ADDRESS (INDEX)
REGISTER (CONFIGURATION STATE ADDRESSING
1
)
0x01
0x03
Watchdog Timer Control (L8 - CRF4)
0x05
0x06
0x08
Soft Power Enable Register 1 (L8-CRB0)
0x09
Soft Power Enable Register 2 (L8-CRB1)
0x0A
Soft Power Status Register 1 (L8-CRB2)
0x0B
Soft Power Status Register 2 (L8-CRB3)
GP1 (L8 - CRF6)
GP5 (L8 - CRF9)
GP6 (L8 - CRFA)
Note 1: These registers can also be accessed through the configuration registers L8 - CRxx, as
shown, when the FDC37B72x is in the configuration state.
GPIO CONFIGURATION
Each GPIO port has an 8-bit configuration
register that controls the behavior of the pin.