查看SX126x的源代码

== Notes ==

=== 硬件笔记 ===

* 2020/12/22: 弃用串口的 RX pin 后，校准 hung 问题解决
* 2020/12/22: 电压一致后，get_status 终于返回 0x22 （avr + sx126x 返回 0x2A）

* 2020/12/23: SPI 读写调整后，重用串口的 RX pin 为  Busy line，居然也没有 hung 问题了，怀疑是 RX 中断没那么频繁了
* 2020/01/21: Send() 后睡眠，电流始终为 900uA，尝试发现，Send() 里，发送后会 set_rx()，删除 set_rx()，睡眠电流降到 1.5uA 左右！

* 板载天线
** 470: 0.2/0.2/0.6/0.4 turns 13
** 472: 0.2/0.2/0.5/0.3 turns 16.5

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=== 软件笔记 ===

<span style="color:#CC0000">'''NOTES：'''</span>

* 用 set_dio_irq_params() 设置 RX_DONE & TIMEOUT & CRC_ERR 中断使能
* 产生的任何一类中断，都会将中断引脚 DIO1 拉高
* 如果不用 clear_irq_status() 清除之，中断引脚 DIO1 则始终是高电平状态，MCU 就无法通过判断引脚上升沿接收中断，但此时 irq_status 寄存器的状态还是更新的，因此 polling 模式不受影响
* RX 接收中断处理里，CRC ERR 可以作为粗过滤，crc_err 的包，check_mic 肯定无法通过。crc 没有 err 的包，有部分 check_mic 也无法通过。。。

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=== Busy Ctrl Line ===

Used to indicate the status of the internal state machine. The BUSY line is set back to zero once the chip has reached a stable mode and it's ready for a new command

* Sleep 模式下，始终为 HIGH (20 kΩ上拉）。唤醒后，BUSY 转 LOW
* In FS, BUSY goes low when the PLL is locked.
* In RX, BUSY goes low as soon as the RX is up and ready to receive data. 
* In TX, BUSY goes low when the PA has ramped-up and transmission of preamble starts.
* In handle its internal IRQ, the BUSY also goes high. In this scenario, it is essential to wait for the BUSY line to go low before sending an SPI command (either a “read” or “write” command).
* All “write” commands cause the BUSY line to be asserted high after time Tsw,as per the graph above. Tsw represents the time required for the internal state machine to wake-up and start processing the command.  
* Conversely, the “read” command is handled directly without the help of the internal state machine and thus the BUSY line remains low after a “read” command.

The max value for Tsw from NSS rising edge to the BUSY rising edge is, in all cases, 600ns.

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=== RF Switch ===

* DIO2 控制 RF Switch 之 ctrl，用于切换 RF1 (RF_OUT) 还是 RF2 (RF_IN) 连接到 RFC (ANT)


对于 RF switch PE4259:

* Pin 6 (~CTRL) = VDD (3.3V Max), Pin 4 (CTRL) = High ------> RF1 (RFO, Pin1) -> RFC
* Pin 6 (~CTRL) = VDD (3.3V Max), Pin 4 (CTRL) = Low  ------> RF2 (RFI, Pin3) -> RFC

[[文件:PE4259.pinmap.png]]

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