RIGADO BMD-34 EVAL Series, Руководство пользователя

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BMD-34x-EVAL User Guide Rev 2.0
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6.5 Virtual COM Port
The evaluation board allows for easy serial communication with the BMD-34x Modules and a
connected computer. The Interface IC provide a virtual COM USB device that connects to 4 GPIO pins
on the module, allowing for UART communication with or without hardware flow control. The UART
lines can be completely removed from the circuit by breaking the associated jumpers.
BMD-3 xx
Pin Name
BMD-3 xx
Function
Jumper Interface
IC
Function
P0.05 RTS J05 CTS
P0.06 TXD J06 RXD
P0.07 CTS J07 TRS
P0.08 RXD J08 TXD
Table 3 – Virtual COM Port
6.6 32kHz Crystal Oscillator
The evaluation board has a 32.768kHz Crystal Oscillator connected to the BMD-3xx module by default.
This allows the module to use any of the three available low frequency (LF) clock sources: an internal
calibrated RC oscillator, an internal synthesized clock (derived from the 32MHz clock), or an external
crystal oscillator. The external crystal oscillator is the most accurate and lowest power LF clock
option. For applications without strict time keeping requirements, the internal calibrated RC oscillator
is often suitable. The crystal is connected to the module through a solder select jumper, allowing
either the crystal or the IO header to be connected to the module’s GPIO pins.
Figure 9 – Schematic - 32KHz Crystal