topic Re: Does the ROM Bootloader in the KL27 support RS485 loading of firmware? in MCU Bootloader

Does the ROM Bootloader in the KL27 support RS485 loading of firmware?

paulmerana — Thu, 09 Mar 2017 00:33:56 GMT

Hi there. I hope this question has not been solved elsewhere. I have a customer who is looking at the KL27 which has the boot loader in ROM and would like the ability to re-flash the device over RS485 instead of serial. Will the boot loader and flashing tool support this provided that the UART to RS485 transceiver has an automatic direction setup? I know with a soft boot loader it can be done and I have seen it mentioned in a few places however I do not see any mention of the parts with the boot loader in ROM.

Re: Does the ROM Bootloader in the KL27 support RS485 loading of firmware?

kerryzhou — Wed, 15 Mar 2017 05:59:01 GMT

Hi Paul Merana,

No, the KL27 ROM bootloader can't support the RS485 loading firmware now.

Just as you said, RS485 need to control /RE and DE pin, but the KL27 ROM just support the UART, two pin communication pin, no direction control pin now.

So, if you want to use the RS485 to load the App code, you need to use the flash bootloader and add the according 485 direction control code.

Wish it helps you!

If you still have question, please let me know!

Have a great day,
(my name)

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Re: Does the ROM Bootloader in the KL27 support RS485 loading of firmware?

paulmerana — Wed, 15 Mar 2017 13:19:30 GMT

Hi Kerry

Thank you for the reply. The problem really is not the /RE DE lines as the hardware can be set up for auto direction control similar to the circuit in the link.

http://www.seekic.com/uploadfile/ic-circuit/s201152772159916.gif

The problem would be the traffic timing. Is it purely half duplex or does it need full duplex communications ability?

Thank you

Paul

Re: Does the ROM Bootloader in the KL27 support RS485 loading of firmware?

kerryzhou — Thu, 16 Mar 2017 07:20:27 GMT

Hi Paul Merana,

If your auto direction control circuit can meet the UART baud rate, of course you can use it.

You need to adjust the traffic timing, for example, baud rate is 115200, your time should follow it.

The uart is half duplex communications.

Maybe you can try to find a 485 chip which has the auto control function.

Have a great day,
Kerry