Hello,
I am designing a custom board with RA2L1 as the host MCU. The board needs to a have a switch to reset the MCU as mandatory. The idea is to use E2 as the programmer. And I am following the guide - https://www.renesas.com/us/en/document/mat/e2-emulator-e2-emulator-lite-additional-document-users-manual-notes-connection-ra-devices to make the hardware schematics.
Please advise on:
I find it astonishing that the evaluation board or other application specific boards that are made available for reference all force the use of another chip for programming and doesn't include schematics to show how to program to RA2L1 directly.
Please find the schematics of the 2x5 (10pin) 1.27mm connector for programming, a switch to RESET the MCU and a switch to select the boot option of the MCU. I have mentioned the pin names near the global labels to identify which pins the global labels connects to on the MCU.
Thanks for posting your question online.
1) You don't need to connect the MD Pin, when using SWD interface. Also, your Boot Mode Selector circuit using SW4 ( or using a jumper) is enough to set the MD pin to 0, in order to start SCI boot mode ( if you need it).
2) The open collector circuit isn't mandatory, your uc Reset circuit is enough, in order to reset your system by hardware.
3) The pins and your circuits seem to be ok.
Regards,
AL_Renesas
Hello Al, 1. Can you tell me when the MD pin will be required? Like what functionality will I be missing if MD pin is not connected?
2. Okay.
3. Okay.
Thanks for your prompt replies.
Best, Abhijith.
MD pin (P201) is internally pull-up connected, so it isn't mandatory to be connected using your boot mode selector circuit. You have two alternatives:
Υou can use your boot mode selector cirucit, but replace SW4 with a jumper, or you can use the connection on Figure 2.9 with a jumper.
When the jumper connector is open, the MD pin will be 1 and you will enter the mcu to on-chip debugging mode, while if the jumper connector is closed, the MD pin will be 0 and you will enter the mcu to SCI or USB boot Mode
Figure 2.8 is for specific RA devices that support Trustzone and DLM, but your RA2L1 device doesn't support these functionalities, so you don't need to take care of this kind of configuration.
If you leave the MD pin unused, the MD pin state will be 1, so you will be always on Single-chip Mode:
If you want to understand what is SCI boot mode, please take a look below that explains it:
https://www.renesas.com/us/en/document/apn/renesas-ra-family-system-specifications-standard-boot-firmware
Τhis mode refers to standard boot firmware using SCI interface.
AL_Renesas said:jumper connector is closed, the MD pin will be 0 and you will enter the mcu to SCI or USB boot Mode
The MD pin is required to be pulled low only during MCU reset right? Or should it continuously be held low for the RA2L1 to be in SCI mode?
Yes, you are right the MD pin should be low before reset.
You don't need to keep it low continuously, but please be careful that if you reset while MD pin is high, the mcu will transfer again to on-chip debugging mode.
Regards