Chapter 4 Basic Operation; Hardware Design; Programming - Ebyte E49-900M20S User Manual

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Chapter 4 Basic operation

4.1 Hardware design

It is recommended to use a DC stabilized power supply. The power supply ripple factor is as small as possible
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and the module needs to be reliably grounded;
Please pay attention to the correct connection of the positive and negative poles of the power supply,
reverse connection may cause permanent damage to the module;
Please check the power supply to ensure that between the recommended supply voltage, if exceeding the
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maximum, the module will be permanently damaged;
Please check the stability of the power supply. Voltage can not fluctuate greatly and frequently;
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When designing the power supply circuit for the module, it is often recommended to reserve more than 30%
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of the margin, so the whole machine is beneficial for long-term stable operation;
The module should be as far away as possible from the power supply, transformers, high-frequency wiring and
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other parts with large electromagnetic interference;
Bottom Layer High-frequency digital routing, high-frequency analog routing, and power routing must be
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avoided under the module. If it is necessary to pass through the module, assume that the module is soldered to
the Top Layer, and the copper is spread on the Top Layer of the module contact part(well grounded), it must be
close to the digital part of the module and routed in the Bottom Layer;
Assuming the module is soldered or placed over the Top Layer, it is wrong to randomly route over the Bottom
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Layer or other layers, which will affect the module's spurs and receiving sensitivity to varying degrees;
It is assumed that there are devices with large electromagnetic interference around the module that will greatly
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affect the performance. It is recommended to keep them away from the module according to the strength of
the interference. If necessary, appropriate isolation and shielding can be done;
Assume that there are traces with large electromagnetic interference (high-frequency digital, high-frequency
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analog, power traces) around the module that will greatly affect the performance of the module. It is
recommended to stay away from the module according to the strength of the interference.If necessary,
appropriate isolation and shielding can be done;
Try to stay away from some physical layers such as TTL protocol at 2.4GHz , for example: USB3.0;
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The mounting structure of antenna has a great influence on the performance of the module. It is necessary to
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ensure that the antenna is exposed, preferably vertically upward. When the module is mounted inside the case,
use a good antenna extension cable to extend the antenna to the outside;
The antenna must not be installed inside the metal case, which will cause the transmission distance to be
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greatly weakened.

4.2 Programming

The core of this module is CMT2300A，its driving method is SPI，the user can operate according to the
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CMT2300A chip manual；
GPIO1/GPIO2/GPIO3 are general IO port, see CMT2300A manual for details；
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E49-900M20S user manual
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