The RL78 programming/debugging method.

Hello all.
what methods are available for the programming of the RL78 group MCU?
1) bootloader via RX/TX
2) bootloader via TOOL0
3) ?programmer? Protocol A? with pull-up the tool0 pin?
this is all methods?

I read manual r01uh0384ej0300_rl78g10.pdf and found in CHAPTER 21 "ON-CHIP DEBUG FUNCTION".
What is it? where i can find debug command specification? or this protocol is closed and available only in the renesas programmer-
emulator E1 and other?
Thank you.

  • Hi yukor,

    If you use RL78/G10(8bit MCU),

    the protocol is different from other RL78 series(16bit like G13/G14) for RL78/G10, so please contact your supplier.

  • Yes, I know. I will use G10 (R5F10Y16ASP)

    in total, RL78 may programmed only by bootloader? Or E1-Emulator work via bootloader too?

  • Hi yukor,

    I guess E1-Emulator work via bootloader and you can use bootloader command via tool0 I/F.

  • Found this:

    Do you know, it is possible to find the timing and command specification on E1 on-chip debug or this is close information only renesas corporation?

  • Hi,

    E1 debugger/flash programmer can be used for any RL78, with connections thru Tool0 and RESET lines (plus VSS/Ground and VDD if powered by E1).  The ToolRxD and ToolTxD connections are NOT needed.  Please download and install the latest, free RFP (Renesas Flash Programming) V2.05 Software utility from Renesas website.  RFP can be used for G10 MCU and all other RL78 MCUs.

    However, RL78/G10 is a special case.  If the board/system voltage is VDD = 4.0V minimum to 5.5V maximum, there is no issue.  However if the board is limited to VDD <4.0Volt, then a special Low voltage board must be purchased and used for debugging or flashing G10 <4.0Volts.

    Please see these 2 documents:

    r20ut2451ej0100_e510y16lvb.pdf (Low voltage OCD Board for RL78/G10 Groups)

    r20ut2937ej0200_e1e20e2lite_rl78.pdf (E1/E20 Emulator, E2 Emulator Lite)

    Additional Document for User’s Manual

    (Notes on Connection of RL78)

    Supported Devices:

    RL78 Family



  • Hi yukor,

    Now, what are you trying to do?
    a) Debugging RL78/G10 with E1-emulator & Debugger. (CS+,E2studio or IAR IDE)
    b) Flash programming RL78/G10 with E1-emulator & Flash Programmer. (RFP)
    c) Debugging RL78/G10 with a system that you made.(another MCU or FPGA etc.)
    d) Flash programming RL78/G10 with a system that you made.(another MCU or FPGA etc.)

  • Thank you all for your interest in the topic.


    I have know how I can

    " C) Debugging RL78/G10 with a system that you made.(another MCU or FPGA etc.)"

    This is a theoretical question.

    The RL78 MCU have on-chip debugging function. I not found description for this function in renesas RM.

    This is a open documentations?

    Debugging function available ONLY by using renesas's software and hardware E1-Emulator for $150, or it

    is possible to make my own tool for debugging the MCU?

    E.g. For Atmel AVR datasheet have !FULL! description to flash and debug the MCU using by ISP, PARRALEL or JTAG mode (mega16 and

    other) with all timings and command description. But in renesas RM I found only bootloader method (protocol A).

    Sorry for my dummy question :).

  • Hi yukor,

    I see.

    Command of the flash programming is exposed to the user.

    Only RL78/G10, need a user individually request to Renesas.(not in web)

    Unfortunately, it seems Renesas does not publish the on chip debugging command.(not in web)

  • This is what I wanted to know!

    Thank you, Kirin.

    Oh! Unfortunately, not all function is open for user.


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