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Aug 18

Using Radio with S100

Many customers have asked about using S100 with radio. The S100 only has USB on interface connector. Connecting to radio with LV-TTL UART interface would be a problem, a USB host to UART conversion circuit will be needed. We are unable find simple to use  breakout board for such function. So we used a Rasberry Pi Zero and wrote some program to do the job. Below explains how to use Raspberry Pi Zero to connect with S100 and radio for sending and receiving RTK base data.

PDF Guide:

Overall Hookup

Radio Interface Connection, 5V / Ground / UART0_TXD for radio transmitter, 5V / Ground / UART0_RXD for radio receiver.

The Raspberry Pi Zero will send to S100 whatever received from UART0_RXD, and send to UART0_TXD whatever received from S100.

Radio Receiver Hookup. E61-433T30D transceiver is used in our example.

Radio Transmitter Hookup

Setting up your SD card

Before you can power up your Raspberry Pi Zero, you will need to have an Operating System on the SD Card.

Things You Will Need

  • Windows Computer
  • SD Card (at least 4G bytes)
  • SD card adaptor - for your computer if your computer doesn't have one

Step1: Put the SD card in your computer

Insert the SD card into your SD card reader. You can use the SD card slot if you have one, or an SD adapter in a USB port. Note the drive letter assigned to the SD card. You can see the drive letter in the File Explorer, for example E:


Step 2. Download the Raspberry Pi OS image

Download the Raspberry Pi OS image from below download link. Once downloaded, unzip the zip file, the full image is about 4 Gigabytes.

Raspberry Pi OS image URL:


For S100 Base Mode: Transfer from S100 USB to Raspberry Pi UART.

For S100 Rover Mode: Transfer from Raspberry Pi UART to S100 USB.

Here is an alternative download link:



Step 3. Download and Install Win32 Disk Imager

Download the Win32DiskImager utility from the Sourceforge Project page as an installer file, and run it to install the software.

Sourceforge Project page:


Run Win32DiskImager.exe


Step 4.
1. Select the image file you extracted earlier.
2. Select the drive letter of the SD card (Be careful to select the correct drive: if you choose the wrong drive you could destroy the data on your computer's hard disk!)
3. Click 'Write' and wait for the write to complete.
4. Exit the imager and eject the SD card.

Now can insert the SD Card into Raspberry Pi Zero.

The E61-433T30D radio module used for base to rover data transmission need to be configured first, before making wiring connection to Raspberry Pi Zero, to ensure the radio pair can correctly send data from one to the other. Also the radio UART baud rate should be configured to 115200. Please refer to E61-433T30D supporting documents and tools for setup configuration; check with E61-433T30D seller/vendor for technical support.

After the pair of E61-433T30D have been configured, and verified could correctly send data from one to the other without losing data, then can later connect to Raspberry Pi to work with S100. After everything is connected, including S100, can turn on power bank, Raspberry Pi Zero takes about 50 seconds to bootup from SD Card.

For the base, need to perform below S100 setup to switch internal connection to use the USB port for correction data output.

For the rover, need to perform below S100 setup to switch internal connection to use the USB port for correction data input.

After above setting are done, the S100 base should be able to send data to S100 rover over E61-433T30D radio.

To do RTK surveying with the S100 rover, setup & running Lefebure NTRIP Client described in S100 User Guide Appendix A-2-4 still need to be done, to allow 3rd party GIS App access to S100 receiver data.  The NTRIP setup configuration is irrelevant in this case.

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