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Always USB boot after POR, instead of EMMC boot

Associate II

On my custom board I have the following issue, when my board powers up it goes into USB DFU mode instead of booting to EMMC, despite the BOOT pins. When I reset the board manually by taking nrst down, it boots correctly. I followed AN5031. I have discrete SMPS for 3.3/1.2 and 1.35V. I have 10k pull ups on the nrst line with 0.1µF cap. NRST and NRST_CORE are connected to each other with a 0R resistor. The reset of the EMMC is also on that line. The supplies rise in about 500µs to the nominal output voltage. HSE is a 24 MHz oscillator.

Any ideas?

ST Employee


this is a know bug, which will be solved in future silicon revision.

Meanwhile, as an indication, Toshiba THGBMNG5D1LBAIL, THGBMDG5D1LBAIL, and Kingston EMMC04G-M627-X03U operate correctly on the STM32MP157C-EV1 board.

See ES0438: STM32MP151x/3x/7x device limitations

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