At some point, after a painless and great experiencing developing a product based on the Renesas Synergy™ platform, it will be time to pass the product on to production and start the next big project. However, before that next project starts, developers need to put in place a way to program the production image into their product. There are several different ways this can be done such as

  • The Renesas Flash Programmer
  • A stand-alone flash programmer

Each programming method has its own use case. For example, the Renesas Flash Programmer (RFP) is great for small production batches, lab use and for makers. This has the advantage of using the same development tools while keeping the source code under wraps. A stand-alone flash programmer is more appropriate for large production runs or when the product is being manufactured off-site by a third party. In this post, we will explore how to use the Renesas Flash Programmer and use it to program a simple test application to a Synergy SK-S7G2 development board.

 Every Synergy microcontroller can be placed into a programming mode that uses UART9 (Pins P19 and P110) to communicate with the RFP that runs on a Windows host PC. The programming mode can only be entered by pulling the boot mode pin, P21, to ground and then toggling the reset pin. Once the microcontroller restarts, the microcontroller will check the boot mode pin and start-up in the UART programming mode rather than running any application that may be present in memory. Below are the pins locations on the SK-S7G2 board that are required to connect to the flash programmer.


P19 is the microcontroller transmit pin and should be connected to the RX pin on a UART to USB converter. P110 is the microcontroller receive pin and should be connected to the TX pin on a UART to USB converter. Don’t forget to also ground the UART to USB converter. If the UART to USB converter and the SK-S7G2 are both being powered by the PC an extra ground connection is probably not necessary but it’s a good practice to do it anyways. With P21 grounded, the programming mode can be entered by shorting the reset pins with a jumper and then removing the jumper.

With the hardware setup, a new project can then be created in the Renesas Flash Programmer tool through the file menu. There are several options that need to be set in order to successfully communicate with the target board. First, the microcontroller family needs to be selected. In this case, Synergy. A project name and also a project folder need to be selected. At this point, the project settings should look as follows:


The flash programming tool has automatically selected COM and 2 wire UART as the communication interface which is the only interface currently supported by the Synergy microcontrollers. The COM6 port may or may not be the correct port. In order to change and verify the port, simply click the Tool Details button and then select the correct port. Once this is done, press the connect button and the flash programmer will attempt to communicate with the microcontroller through the COM port. If everything goes as expected, the developer will see the device connect and successfully complete the connection operation as shown below:


The microcontroller and the flash programmer are now communicating and a developer can load their software image into the device. In the next post, we will discuss how to go about loading an image along with the various settings that are available in the flash loader utility.


Until next time,

Live long and profit!



Hot Tip of the Week

The Renesas Flash Programmer works with Synergy MCUs as well as other Renesas MCUs so it is a valuable tool to put in your toolkit. Use these helpful links to find out more:

Renesas Flash Programmer V3.03.00 Home Page:

Renesas Flash Programmer V3.03.00 User’s Manual: