у некоторых 1024, у некоторых 2048, поэтому может и не включили в STM32F103xB.h
Ё #if (defined(STM32F101x6) || defined(STM32F102x6) || defined(STM32F103x6) || defined(STM32F100xB) || defined(STM32F101xB) || defined(STM32F102xB) || defined(STM32F103xB)) #define FLASH_PAGE_SIZE 0x400U #endif /* STM32F101x6 || STM32F102x6 || STM32F103x6 */ /* STM32F100xB || STM32F101xB || STM32F102xB || STM32F103xB */ #if (defined(STM32F100xE) || defined(STM32F101xE) || defined(STM32F103xE) || defined(STM32F101xG) || defined(STM32F103xG) || defined(STM32F105xC) || defined(STM32F107xC)) #define FLASH_PAGE_SIZE 0x800U #endif /* STM32F100xB || STM32F101xB || STM32F102xB || STM32F103xB */ /* STM32F101xG || STM32F103xG */ /* STM32F105xC || STM32F107xC */ Ё