Bootloader

To prepare your application for the bootloader on the SP-1, there are a few things to keep in mind:

• The bootloader will write the application starting at 0x20000 in the nRF52840 flash and the application's max size is 0xDEFFF.
• The bootloader starts the watchdog. If your app doesn't keep the watchdog happy, the device will reset after 5 seconds.
• LFCLK and HFCLK and some peripherals like PWM2, PWM3, SAADC are started by the bootloader. If you use the nRF5 SDK to setup your peripherals and clocks, some calls might fail because the SDK assumes they haven't been inited before.
• The SP-1 doesn't have a hard reset. You need to provide a way for the device to go into SYSTEM_OFF to be able to get back to the bootloader.
• RESETREAS needs to be cleared before going back to the bootloader.

You can upload new firmware to your SP-1 with the update utility by Solderless.

⚠️ WARNING

This is a warning for beginners (and reckless experts 😎)

There is no hard reset or reset pin on the SP-1 and no easy way to power cycle the device.
Please fully test new firmware on a device with debugger access before loading it onto a stock SP-1!

Always make sure you can properly reset to bootloader from your firmware!