: Detailed ISP and EMMC/UFS layouts for the STK-L21 can be found on specialized repositories like EMMC-UFS .
If you do not have a specialized schematic diagram, search for "STK-L21 ISP bitmap" on technical forums like GSMHosting. Technicians often post high-resolution photos of the board with the lines marked in red. stk-l21 isp pinout
For simpler tasks like FRP removal that don't require full eMMC access, a single USB Test Point (shorting a point to GND) is often used to put the device into "HUAWEI USB COM 1.0" mode. : Detailed ISP and EMMC/UFS layouts for the