如何在内存受限的嵌入式系统上处理大量数据传输？

I have a microcontroller that must download a large file from a PC serial port (115200 baud) and write it to serial flash memory over SPI (~2 MHz). The flash writes must be in 256 byte blocks preceded by a write command and page address. The total RAM available on the system is 1 kB with an 80 byte stack size.I have a microcontroller that must download a l