8-bit USB device microcontroller: CH551


CH551 is a MCS51 compatible E8051 core microcontroller, 79% instructions of CH551 is single byte or single cycle, and average instruction speed is 8 to 15 times faster than the standard MCS51. CH551 supports up to 24MHz system clock speed, built-in capacitive detection module, 3 timers and 2 PWM, UART, SPI, USB device controller and full-speed transceiver. CH551 is a simplified version of CH552, ROM is 10K, xRAM is 512 bytes, UART0only, package SOP16only, and remove the ADC module and USB type-C module, besides,you may refer directly to the CH552.


  • Enhanced E8051 core CPU, 8-15 times faster than the standard MCS51;
  • Built-in 10KB Code Flash, 512B XRAM and 256B iRAM, 128B DataFlash, support byte read and write;
  • Built-in BootLoader, support USB and UART ISP, provide ISP download library;
  • USB controller and USB transceiver, USB-Device device mode support; support USB 2.0 full speed 12Mbps or low speed 1.5Mbps, support up to 64 bytes of data packets, built-in FIFO, support DMA;
  • 3 timer / counter, support 2-channel signal capture and 2 PWM output;
  • Provide full duplex UART, support high baud rate communication;
  • Provides a SPI, built-in FIFO, support Master / Slave mode;
  • Supports 6-channel capacitance detection;
  • Supports four reset signal sources, built-in power-on reset, support software and watchdog time-out reset, selectable pin external reset;
  • Built-in 24MHz clock source and PLL;
  • Built-in 5V to 3.3V LDO that supports 5V or 3.3V or even 2.8V voltagesupply. Support low power sleep, support USB, UART0, SPI0 and some GPIO wake-up;
  • Built-in unique ID number;
  • Package: SOP-16.

Develop resources

ISP download mode: USB interface or UART

  1. CH551DS1.PDF (datasheet)
  2. ISP download software, WCHISPTool_Setup.exe
  3. CH551 sample program (C language)
  4. CH551 development board schematics and PCB