Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32h7/STM32H750/JPEG/JPEG_CONFR0#0x0
JPEG codec control register
Start This bit start or stop the encoding or decoding process. Read this register always return 0.
https://github.com/modm-io/cmsis-svd-stm32