I need help about bootloader on Kinetis MKL17Z256VFM4. I already used MC9S08 and Coldfire MCU, but it's the first time that I use Kinetis MCU.
Moreover, it's the first time that I will work with bootloader. So certainly I will ask very simply questions or questions with logical answers but as I'm beginner in bootloader, even if I think to know the answer, I need certainties on this subject to avoid errors.
1) In a first time, I want to implement a bootloader via UART :
1.1) Is it possible to use an "UART to USB" component between the UART of the MCU and the PC in the aim to have an USB bootloader ? I suppose baudrate on USB will be limited by the max baudrate of the UART ?*
1.2) I read that KL17 have a bootloader in ROM. So in fact, with this, I just to point on the adress of the bootloader to launch it when I want in my program as it said here : Call ROM Bootloader from customer application with FRDM-KL43Z board (the last section) ?
1.3) Not about the bootloader : I don't really understand the difference between UART and LPUART, what's the criterias to use one or the other ?
2) In a second time, I will implement the bootloader via a BLE connected to UART.
For this I think it's mandatory to store previously the datas in an external flash (by the application) and after launch the bootloader so that it goes to read the external flash and reprogramming MCU flash.
2.1) I suppose the external flash size have to be equal than the MCU flash to program (256kB in my case)
2.2) MKL17 already have a ROM bootloader. Have I to erase this bootloader with my own bootloader ? Or can I write a "second" bootloader and pointed to it when needed ?
For the point 2), I'm not sur how to manage bootloading by BLE, all ideas are welcome!