Datasheet

Dual Serial UART with 128-Word FIFOs
MAX3109
48 Maxim Integrated
GPIO Data Register (GPIOData)
Each UART has four individually assigned GPIO outputs as follows: UART0: GPIO0–GPIO3, UART1: GPIO4–GPIO7.
Bits 7–4: GPIxDat
The GPIxDat bits reflect the input logic on the associated GPIO_s. For example, for UART1: GP0Dat configures GPIO4,
GP1Dat configures GPIO5, GP2Dat configures GPIO6 and GP3Dat configures GPIO7. When configured as inputs in
GPxOut, the GPIO_s are high-impedance inputs with weak pulldown resistors, regardless of the state of GPxOD.
Bits 3–0: GPOxDat
The GPOxDat bits allow programming of the logic state of the GPIO_s when configured as outputs in GPIOConfg[3:0].
For open-drain operation, pullup resistors are needed on the GPIOs. For example, for UART1: GP0Dat configures
GPIO4, GP1Dat configures GPIO5, GP2Dat configures GPIO6 and GP3Dat configures GPIO7.
ADDRESS: 0x19
MODE: R/W
BIT 7 6 5 4 3 2 1 0
NAME
GPI3Dat GPI2Dat GPI1Dat GPI0Dat GPO3Dat GPO2Dat GPO1Dat GPO0Dat
RESET
0 0 0 0 0 0 0 0