After analyzing multiple motherboard revisions (Cambridge 1.0, 2.0), the ISP test points for the STK-L21 are consistent. The eMMC chip is usually a Toshiba or Samsung model, but the pinout remains the same.
To connect the device via ISP, you must solder tiny wires to specific test points on the motherboard to establish a connection with the eMMC chip. The standard required connections are: : Data line 0. : Command line. : Clock line. VCC (2.8V - 3.3V) : Power for the eMMC. VCCQ (1.8V) : I/O voltage for the eMMC. Technical Resources stk-l21 isp pinout
Some technicians use the back side of the board under the eMMC shield. Remove the metal shield carefully using heat (300°C hot air). You will find small vias labeled CMD , CLK , and D0 . After analyzing multiple motherboard revisions (Cambridge 1
The STK-L21 dev board exposes programming pads or pins for the STM32L021F4P6. While manufacturer silk and schematics should be consulted for exact pad labels, the mapping follows STM32L0 reference pins: The standard required connections are: : Data line 0