The RN4020 Device Firmware Update (DFU) Utility can be used to perform a firmware update on the RN4020 Bluetooth Low Energy module using a wired connection over the Universal Asynchronous Receiver/Transmitter (UART) interface. This utility can be used for both RN4020 firmware upgrade and downgrade needs. As with any DFU process, a firmware upgrade should be handled carefully to avoid unrecoverable damage to the device.
If an upgrade fails for any reason, keep the RN4020 module alive and try to recover by applying the DFU process again. The following conditions must be met when the RN4020 module performs a DFU through the UART:
- UART hardware flow control (RTS/CTS) must be used
- No UART communication other than streaming the DFU image
- No RF communication attempts. All other operations during a DFU period should be avoided
- While the DFU is in progress, RN4020 should not be disconnected and DFU process should not be interrupted. If the DFU process is interrupted the RN4020 module might end up bricked.
- Use a valid Microchip released RN4020 DFU (.bin) file only. Using an invalid DFU (.bin) file will result in a bricked module.
- This utility CANNOT be used to unbrick the module.
- If the module gets bricked please contact a Microchip Sales Representative to get the issue resolved.
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This lab requires the following software tools:
The RN4020 DFU Utility must be able to enter commands that place the RN4020 into UART DFU mode. FLOW CONTROL MUST ALSO BE USED! The following signal connections are required at a minimum:
If the RN4020 module UART signal lines are connected to a host MCU, we advise placing the host MCU in reset (via a grounding jumper wire connected to the MCLR pin) to relinquish control of these lines during the DFU process.
Wait for the RN4020 PICtail to enumerate as a Serial Port device successfully.
Run the RN4020 DFU Utility (RN4020DFUUtility.exe) on the Windows PC. The DFU Utility can be downloaded from www.microchip.com/rn4020. It is located under Documentation -> Software -> RN4020 Firmware vx.xx Update.
Ensure that the RN4020 PICtail is still connected to the Windows PC and successfully enumerated. Click ‘Scan’ button to scan for all the UART COM ports available on the Windows PC.
Ensure that the COM port on which the RN4020 PICtail is enumerated is not already open by another application like a Serial Terminal application.
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Be sure to use a valid Microchip released RN4020 DFU (.bin) file only. Using an invalid DFU (.bin) file will result in a bricked module.