> 3.17 | GPIO Interface

> The TC65 has 10 GPIOs for external hardware devices. Each GPIO can be configured for use as input or output. All settings are AT command controlled.
> The GIPO related AT commands are the following: AT^SPIO, AT^SCPIN, AT^SCPOL, AT^SCPORT, AT^SDPORT, AT^SGIO, AT^SSIO. A detailed description can be found in [1].
> When the TC65 starts up, all GPIO pins are set to high-impedance state after initializing, as described in Section 3.3.2. Therefore, it is recommended to connect pull-up or pull-down resistors to all GPIO pins you want to use as output. This is necessary to keep these pins from floating or driving any external devices before all settings are done by AT command (at least AT^SPIO, AT^SCPIN), and after closing the GPIOs again.