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ZBasic Language Reference 158 ZX Microcontroller Family By default, the serial connection to the ZX-24 series devices is 19.2K baud. You can operate the serial channel at higher and lower speeds by explicitly opening the COM1 serial channel. See the description of OpenCom() in the ZBasic System Library Reference manual. The simple configuration shown above is limited by the capacity of the on-board regulator. Although it will work for simple systems, many users will benefit from powering the ZX-24 series device from an externally regulated source. A suggested connection for such a configuration is shown below. (Note that a different regulator must be used for the ATxmega-based ZX devices; one that provides 2.6-3.6V.) The output of the external regulator can also be used to power additional external circuitry up to the capacity of the regulator. Depending on the power dissipated by the regulator, it may need to be mounted on a heat sink to prevent it from getting too hot. ZX-24 Series Device Interconnection Using an External Regulator This configuration also shows how to connect a reset switch. A reset switch is sometimes useful, particularly during debugging, to get the ZX to start running its program from the beginning. If the reset is also connected to other external circuitry, you may wish to isolate the ZX from the remaining circuitry so that the on-board resets that occur during downloading are not also applied to the external devices. A simple isolation circuit employing a small signal diode is shown below. You can also implement an isolation circuit using a discrete transistor or an open-collector gate. Reset Signal Isolation