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2016
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6.1.11
General Purpose Input/Output
The conga-TR3 offers general purpose inputs and outputs for custom system design. These GPIOs are multiplexed with SD/SDIO signals and
are controlled by the cBC.
Note
The GPIO/SD selection is done via the BIOS setup menu.
6.1.12
Serial Ports/UART Interfaces
Two TTL compatible two wire ports are available on Type 6 COM Express modules. These pins are designated SER0_TX, SER0_RX, SER1_TX
and SER1_RX. Data out of the module is on the _TX pins. Hardware handshaking and hardware flow control are not supported. The module
asynchronous serial ports are intended for general purpose use and for use with debugging software that make use of the “console redirect”
features available in many operating systems.
The conga-TR3 offers two UART interfaces via the congatec Board Controller. The UART controllers integrated in the cBC support up to
1MBit/s and can operate in low-speed, full-speed and high-speed modes. The UART interfaces are routed to the AB connector and require
congatec driver to function.
Note
The UART interfaces do not support legacy COM port emulation.
6.1.13
Power Control
PWR_OK
Power OK from main power supply or carrier board voltage regulator circuitry. A high value indicates that the power is good and the module
can start its onboard power sequencing. The PWR_OK is a 3.3V signal according to the COM Express Specification. The use of this input is
optional.
Carrier board hardware must drive this signal low until all power rails and clocks are stable. Releasing PWR_OK too early or not driving it low
at all can cause numerous boot up problems. It is a good design practice to delay the PWR_OK signal a little (typically 100ms) after all carrier
board power rails are up, to ensure a stable system. Although the PWR_OK input is not mandatory for the onboard power-up sequencing, it is
strongly recommended that the carrier board hardware drives the signal low until it is safe to let the module boot-up.
