Software Design - Ebyte E220-400MM22S User Manual

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Bottom Layer High-frequency digital routing, high-frequency analog routing, and power routing must be avoided
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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 Layer
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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 analog,
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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;
It is not recommended to use 5V level for communication lines, and there is a risk of damage. A level conversion
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circuit needs to be added;
The antenna installation structure has a great influence on the performance of the module. Make sure that the
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antenna is exposed, preferably vertically upward. When the module is installed inside the case, a high-quality
antenna extension cable can be used to extend the antenna to the outside of the case;
The antenna must not be installed inside the metal shell, which will greatly weaken the transmission distance;
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It is recommended to add a 200R protection resistor to the RXD/TXD of the external MCU.
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4.2 Software Design

This module is LLCC68+ peripheral circuit, users can operate according to LLCC68 chip book;
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DIO1, DIO2, and DIO3 are general-purpose IO ports, which can be configured with various functions; DIO2 can be
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connected with TXEN, not with the IO port of MCU, and is used to control the RF switch transmission, see
LLCC68 manual for details, if not used, it can be left floating;
Internal use of 32MHz passive crystal, no pin control, software program control;
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Difference between LLCC68 and SX1262/SX1268:
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1. SX1262/SX1268 support spreading factors SF5, SF6, SF7, SF8, SF9, SF10, SF11, SF12;
LLCC68 supports spreading factors SF5, SF6, SF7, SF8, SF9, SF10, SF11.
2. Spread spectrum factor and receiver bandwidth that can be set by LLCC68:
LoRa® Rx/Tx, BW = 125 – 250 - 500 kHz,
LoRa®，SF = 5 - 6 - 7 - 8 - 9 for BW = 125 kHz,
LoRa®，SF = 5 - 6 - 7 - 8 - 9 - 10 for BW = 250 kHz,
LoRa®，SF = 5 - 6 - 7 - 8 - 9 - 10 - 11 for BW = 500 kHz;
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E220-400MM22S User Manual