Communicating with your Reader
A guide for Gemini and Nova RFID modules.
This is a quick-start guide for basic board-level communication with your RFID module. Before beginning, please ensure the following criteria are met:
- SkyeWare is installed and working on your PC
- Your RFID module is detected by USB connection in SkyeWare
- Your module is independently powered (It can NOT be powered by USB for non-USB communication.)
- A method to communicate with your module. This can be a micro-controller, PC Adapter, Logic Analyzer, etc. You may use:
Basic communication with your RFID module is designed to be efficient and consistent across multiple interfaces. In order to get the most out of your reader module, please familiarize yourself with the SkyeTek Communication Protocol. This guide also covers other important topics such as Binary vs. ASCII formats, data timing, and multiple-byte requests.
Note: After start-up, the Nova will hold an amber light on until an interpretable command is received (i.e. if a serial port is configured for a wrong baud rate, the amber light will still be on after sending the bad command).
The default communication interface for the reader is USB. This is the easiest method for communicating with your reader and is represented with an HID driver in your host device. The SkyeTek API is designed to use USB natively and offers a streamlined API for controlling the module. For more information on the API, check out the SkyeTek API Guide.
IMPORTANT: When USB is connected it will override ALL other interfaces – even if a different interface is written as default.
There are no additional driver downloads required to use your module via USB. If you cannot see your module after connecting by USB, please check out the troubleshooting sections to help solve your problem.
The RS-232 / TTL interface can be considered the secondary external communication port to your module. It supports both Binary and ASCII modes, and includes full support from the SkyeTek API in custom applications. To switch from USB to TTL communication:
- Open Skyware (with the module connected by USB)
- Go to ‘Configuration’ and select ‘Serial’ from the “Host Interface” dropdown box.
- Click “Set as Default” then “Apply”
- Disconnect USB from your module (do not reconnect)
- Power Cycle
From there, you can communicate via TTL with either ASCII or Binary mode.
Warning: You must use a translator circuit if communicating from RS-232 voltage levels from a PC. A pre-built solution can be found here.
- The default baud rate is 38,400 (9,600 to 115,200 available)
- Bytes are transmitted LSB first
- 8-data bits, no parity, 1 stop bit (8N1)
- 3.3V and 5V levels supported
- PC Interface must be COM1-COM9 in order to talk to SkyeWare
SPI / I2C Communication
The SPI / I2C communication modes serve as the primary interfaces for low-level communication between embedded devices. Supporting only binary mode, these two interfaces allow for a clean embedded solution for any product that implements these communication standards. In order to successfully utilize these interfaces, some advanced configuration is required.
In order to enable these ports, follow the same steps as the Serial communication interface above, except selecting SPI or I2C as applicable. Remember to disconnect USB from your module prior to power cycling.
After power cycling, your selected port should be available for use. Your master device should take the following configuration into consideration in order to successfully communicate:
- The host must implement SPI Master functionality.
- Polarity is Rising / Falling
- Phase is Setup / Sample
- Data is sent MSB first
- Slave Select is Active Low
- Bitrate default is 1000Hz (up to 4 MBit)
- The host must implement I2C Master functionality.
- Data is sent MSB first
- 7-bit addressing
- Address default: 0x7F (can be changed by system)
- The standard message length can vary depending on the command given, but will report repeat / junk data if you read over the response length.
For more information on SPI / I2C protocol, hardware layout, and timing diagrams, review the Product Spec Sheet.