Debug the si4438 series modules

The si4438 series is different from the previous si4432 and has changed in many places.

• Frequency Range: 425-525 MHz
• Receiving sensitivity-124dbm
• Modulation method (g) 2XX ook
• Maximum output power + 20dbm
• Low Energy Consumption14mA
• Transmission Rate: 100bps ~ 500 kbps
• Operating voltage: 1.8-3.6 V
• Low Voltage Detection
• Chip internal temperature detection

The main register configurations can be configured in the official WDS software, basically meeting the needs of most applications. When encountering some complex applications, you must manually configure specific registers. For specific register configurations, refer to the official API documentation.

This chip is divided into package mode and pass-through mode. The package Mode means that the chip is packaged and unpackaged. When receiving valid data, it will notify the MCU in the form of interruption. These packages are packaged in a certain format. The first is the forward guide code. Generally, the package is 0101 or 1010, greater than 5 bytes. The forward guide code is useful for Chip detection and identification, and for frequency correction. Because the sending and receiving frequencies are always the same, you can use the forward guide code for correction.

The synchronization word and the synchronization word can further improve the data validity. Many remote control manufacturers use synchronous words as device IDs to send and receive data one by one. Generally, when a device is connected to a controlled device, the remote control and the controlled device need to perform a pair of codes. The controlled device sends the ID to the remote control. Of course, the synchronization word is pre-defined by the manufacturer and is fixed. After a code pair, the remote control can only control the device with the corresponding ID as long as the code is not re-aligned. A maximum of 4 bytes can be synchronized.

Then there is data. When setting data in WDS, you can select a fixed length or a non-fixed length to save the first byte length value of the data packet. A non-fixed length must have a length value. You can use the option to put the length in FIFO or not.

When receiving and sending data in package mode, pay attention to the transmission. If the expected length of receiving and sending is shorter than the actual length, in this case, the excess data is intercepted.

 

The pass-through mode is the most primitive high-level output. This mode is mainly used to communicate with chips of different manufacturers. However, it requires the MCU to handle packaging and unpackage tasks. In my actual debugging, although the nirq and SDO scripts in WDS can choose to send data input, in actual debugging, I found that these two scripts are invalid. The input for sending data must be the gpio's four feet.

I don't know why. When ook is adjusted to 5 K or above, the chip that receives the output is messy. When there is no signal, it is also continuous up and down. When receiving a base-to-base Load balancer in the pass-through mode, the base-to-base Load balancer is in a continuous state. Only when receiving a base-to-base Load balancer signal is the base-to-base Load balancer, this makes it very troublesome to parse the 'base. Especially when you don't know when the data will come.

 

Currently, most 433 sensors adopt the OOK modulation mode, and the key-value-1 is a minority. Sensor manufacturers basically use 430 series single-chip microcomputer to achieve the purpose of low power consumption.