Kinetis MKE14 bootloader in half duplex RS485 mode

[rudycoppens]

Used hardware:

- Kinetis MKE14

- LTC2862 RS485 half duplex transceiver

Software:

- MCUXpresso 10.2

I would like to use the build in bootloader but this implementation is standard full duplex. Is there a way or option to make it work for half duplex? 

If not were can I found the bootloader source code so thatI can change it? 

Thx!

[kerryzhou]

Hi Rudy,

    Please check the ROM bootloader:

You can find it just have TX and RX, no the direction control, so the ROM UART bootloader can't support the 485 directly.

You need to write the flash bootloader, can't use the ROM bootloader for 485.

Have a great day,
Kerry

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[rudycoppens]

Thanks for your response! Do you know were I can find a standard flash bootloader?

[mjbcswitzerland]

Hi Rudy

In case you have problems (or need to avoid porting time and expense) there are KBOOT compatible loaders in the uTasker project (see below), also for KE parts.
To use RS485 mode you just need to call
fnDriver(SerialPortID, (MODIFY_CONTROL | CONFIG_RTS_PIN | SET_RS485_MODE), 0); // configure RTS pin for control use
after the Kboot UART configuration.

The KE15 (KE14's) LPUART supports automatic RS485 direction control.

Regards

Mark

Kinetis: http://www.utasker.com/kinetis.html
Kinetis KE:
- http://www.utasker.com/kinetis/FRDM-KE02Z.html
- http://www.utasker.com/kinetis/FRDM-KE02Z40M.html
- http://www.utasker.com/kinetis/FRDM-KE04Z.html
- http://www.utasker.com/kinetis/FRDM-KE06Z.html
- http://www.utasker.com/kinetis/FRDM-KE15Z.html
Serial Loader Guide: http://www.utasker.com/docs/uTasker/uTaskerSerialLoader.pdf

[kerryzhou]

Hi Rudy,

You can refer to this application note:

https://www.nxp.com/docs/en/application-note/AN4767.pdf 

https://www.nxp.com/docs/en/application-note-software/AN4767SW.zip 

Then add the 485 EN pin with GPIO control.

Wish it helps you!

Have a great day,
Kerry

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