Datasheet

Dual Serial UART with 128-Word FIFOs
MAX3109
47Maxim Integrated
XOFF2 Register
The XOFF1 and XOFF2 register contents define the XOFF character for automatic XON/XOFF flow control and/or the
special characters used in special character detection. See the FlowCtrl register description for more information.
Bits 7–0: Bitx
These bits define the XOFF1 character if single character XOFF auto software flow control is enabled in FlowCtrl[7:4].
If double character flow control is selected in FlowCtrl[7:4], these bits constitute the least significant byte of the 2-byte
XOFF character. If special character detection is enabled in MODE2[4] and auto software flow control is not enabled,
these bits define a special character.
If both special character detection and auto software flow control are both enabled, XOFF2 defines a special character.
GPIO Configuration Register (GPIOConfg)
Each UART has four GPIOs that can be configured as inputs or outputs and can be operated in push-pull or open-drain
mode. The reference clock needs to be active for the GPIOs to work.
Each UART has four individually assigned GPIO outputs as follows: UART0: GPIO0–GPIO3, UART1: GPIO4–GPIO7.
Bits 7–4: GPxOD
Set the GPxOD bits high to configure the associated GPIOs as open-drain outputs. Set the GPxOD bits low to configure
the associated GPIOs as push-pull outputs. For example, for UART1: GP0OD configures GPIO4, GP1OD configures
GPIO5, GP2OD configures GPIO6 and GP3OD configures GPIO7.
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.
Bits 3–0: GPxOut
The GPxOut bits configure the associated GPIO_s to be either inputs or outputs. Set the GPxOut bits high to configure
the associated GPIO_s as outputs. Set the GPxOut bits low to configure the associated GPIO_s as inputs. For example,
for UART1: GP0Out configures GPIO4, GP1Out configures GPIO5, GP2Out configures GPIO6 and GP3Out configures
GPIO7.
ADDRESS: 0x17
MODE: R/W
BIT 7 6 5 4 3 2 1 0
NAME
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
RESET
0 0 0 0 0 0 0 0
ADDRESS: 0x18
MODE: R/W
BIT 7 6 5 4 3 2 1 0
NAME
GP3OD GP2OD GP1OD GP0OD GP3Out GP2Out GP1Out GP0Out
RESET
0 0 0 0 0 0 0 0