https://github.com/leaflabs/maple/blob/master/maple-r5/maple-r5-schematic.pdf

STM32 F103RB: a 32-bit ARM Cortex M3 microprocessor
Clock Speed: 72 MHz
Operating Voltage: 3.3V
Input Voltage (recommended): 3.0V-12V
39 Digital I/O Pins (GPIO)
16 Analog Input Pins
12-bit ADC resolution (ADC)
15 PWM pins at 16-bit resolution (PWM)
Dedicated USB port for programming and communications (USB)
External JTAG interface (USB)
128 Flash and 20KB SRAM
64 Channel nested vector interrupt handler (including external interrupt on GPIO’s)
Integrated SPI (SPI)
Integrated I2C (I2C)
7 Channels of Direct Memory Access (DMA)
3 USART devices
Four 4-channel Timers (Timers)
Supplies up to 500mA @ 3.3v
Support for low power and sleep modes (<500uA)

serial flash

Press boot 0, press reset, release reset, release boot 0

dpavlin@nuc:/nuc/stm32$ git clone https://github.com/jsnyder/stm32loader

dpavlin@nuc:/nuc/stm32/stm32loader$ ./stm32loader.py -p /dev/ttyUSB0 
Bootloader version 22
Chip id: 0x410 (STM32 Medium-density)

dpavlin@nuc:/nuc/stm32/stm32loader$ ./stm32loader.py -p /dev/ttyUSB0 -e -w -v ../blackmagic/src/blackmagic_dfu.bin 
Bootloader version 22
Chip id: 0x410 (STM32 Medium-density)
Write 256 bytes at 0x8000000
Write 256 bytes at 0x8000100
...
Read 256 bytes at 0x8001900
Read 256 bytes at 0x8001A00
Verification OK

dpavlin@nuc:/nuc/stm32/stm32loader$ ./stm32loader.py -p /dev/ttyUSB0 -w -v -a 0x8002000 ../blackmagic/src/blackmagic.bin 

maple boot loader

dpavlin@nuc:/nuc/stm32/stm32loader$ wget http://docs.leaflabs.com/static.leaflabs.com/pub/leaflabs/maple-bootloader/maple_boot.bin

dpavlin@nuc:/nuc/stm32/stm32loader$ ./stm32loader.py -p /dev/ttyUSB0 -e -w -v maple_boot.bin

STM32 Arduino upgrade

bootloader

• https://github.com/rogerclarkmelbourne/STM32duino-bootloader

dpavlin@nuc:/nuc/stm32/stm32loader$ wget https://github.com/rogerclarkmelbourne/STM32duino-bootloader/raw/master/STM32F1/binaries/maple_rev5_boot20.bin

maple r5 is not reported with dfu-util

https://github.com/rogerclarkmelbourne/STM32duino-bootloader/pull/20