Notes For Hardware And Software; Hardware Design - Ebyte E22-900M33S User Manual

Chengdu Ebyte Electronic Technology Co., Ltd.

4 Notes for hardware and software

4.1 Hardware design

It is recommended to use a DC regulated power supply to power the module. The power supply ripple coefficient should be as
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small as possible, and the module must be reliably grounded;
Please pay attention to the correct connection of the positive and negative poles of the power supply. Reverse connection may
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cause permanent damage to the module;
Please check the power supply to ensure that it is within the recommended power supply voltage. If it exceeds the maximum
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value, it will cause permanent damage to the module;
Please check the stability of the power supply. The voltage cannot 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% margin, so that the

whole machine can work stably for a long time;
The module should be kept as far away as possible from power supplies, transformers, high-frequency wiring and other parts
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with high electromagnetic interference;
High-frequency digital traces, high-frequency analog traces, and power traces must be avoided under the module. If it is

absolutely necessary to pass under the module, assuming that the module is welded on the Top Layer, lay copper ground on the
Top Layer of the module contact part (all copper and well grounded), it must be close to the digital part of the module and routed
on the Bottom Layer ;
Assuming that the module is welded or placed on the Top Layer, it is also wrong to route traces randomly on the Bottom Layer
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or other layers, which will affect the module's spurious and receiving sensitivity to varying degrees ;
Assuming that there are devices with large electromagnetic interference around the module, which will also greatly affect the

performance of the module, it is recommended to stay away from the module according to the intensity of the interference. If the
situation allows, appropriate isolation and shielding can be done;
Assuming that there are traces with large electromagnetic interference around the module (high-frequency digital,

high-frequency analog, power traces), it will also greatly affect the performance of the module. It is recommended to stay away
from the module according to the intensity of the interference. If the situation allows, you can make appropriate adjustments.
isolation and shielding;
If the communication line uses 5V level, a 1k-5.1k resistor must be connected in series (not recommended, there is still a risk of
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damage) ;
Try to stay away from some TTL protocols whose physical layer is also 2.4GHz, such as USB3.0;
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The antenna installation structure has a great impact on module performance. Make sure the antenna is exposed, preferably
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vertically upward. When the module is installed inside the case, you can use a high-quality antenna extension cable to extend the
antenna to the outside of the case;
The antenna must not be installed inside a metal shell, as this will greatly reduce the transmission distance.
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to add a 200R protection resistor to the RXD/TXD of the external MCU .
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E22-900M33S User Manual
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