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A command line programmer for STC 8051 microcontroller.

The programmer software provided by STC for their 8051-compatible microcontrollers (MCUs) only runs on Microsoft Windows. For developers who are more used to other operating systems, this project, named stcflash, provides a more convenient way to download program to STC 8051 microcontroller across different platforms. Other than its portability, stcflash also has the advantage of employing a simple command line interface, so integrating it in a development toolchain is fairly easy.


Python (>=2.6) and its serial port extension model pySerial are required to run stcflash. Python is most likely pre-installed if you are using a mainstream Linux distribution or OS X. Module pySerial, on the other hand, might need to be installed manually. For example, on some versions of Ubuntu, you must install package python-serial (or python3-serial for Python 3) to get pySerial. For operating system without a package management system like Windows, please refer pySerial's installation manual for further assistance.

How to use

To read model information from the target microcontroller, simply run stcflash without giving any parameter.

$ python
Connect to /dev/ttyUSB0 at baudrate 2400
Detecting target... done
 FOSC: 11.955MHz
 Model: STC89C52RC (ver4.3C)

Please note that, just like using the official STC programmer, once the "Detecting target..." prompt is shown, you need to turn off and on the microcontroller to enable the in-system programming (ISP) routine, otherwise, stcflash cannot connect to the target.

If the microcontroller hooks up to a different port than the first USB-to-serial port, you can use --port to specify the name of the port. It is also possible to specify a different initial baudrate using --lowbaud option, although this should not be necessary in most cases. Here is an example,

$ python --port /dev/ttyUSB1 --lowbaud 1200
Connect to /dev/ttyUSB1 at baudrate 1200
Detecting target...

This program can download compiled code in either binary (.bin) or Intel HEX (.ihx/.hex) format into the target microcontroller like the following example,

$ python program.hex
Connect to /dev/ttyUSB0 at baudrate 2400
Detecting target... done
 FOSC: 11.955MHz
 Model: STC89C52RC (ver4.3C)
Baudrate: 38400
Erasing target... done
Size of the binary: 917
Programming: #################### done

For now, stcflash supports the following series of MCUs and their low voltage variants.

STC89C5xRC, STC89C5xRD+, STC90C5xRC, STC10Fxx, STC11Fxx, STC12Cx052x, STC12C52xx, STC12C56xx, STC12C5Axx

If stcflash is unable to detect the microcontroller, forcing the programming protocol using --protocol option might solve the problem. For example, if a microcontroller uses the same programming protocol as STC89C5xRC series, then you can program it as follows,

$ python --protocol 89 program.bin

The following is a table of protocols and corresponding MCUs that have been tested working with each protocol.

Protocol MCUs
89 STC89C52RC (v4.3C), STC89C54RD+ (v4.3C), STC90C52RC (v4.3C)
12cx052 STC12C2052 (v5.8D)
12c52 STC12C5608AD (v6.0G), STC12C5204AD (v6.0H)
12c5a STC10F04XE (v6.5J), STC12C5A16S2 (v6.2I), STC11F02E (v6.5K)

Before connecting to a microcontroller using one of the ISP protocols, stcflash can send a magic word first at a given baudrate to ask the microcontroller to enter ISP mode without user switching its power off and on. Please note that the user program on the microcontroller must be able to reboot itself to the ISP section upon receiving the magic word to make this scheme work. The following is an example,

$ python --aispbaud 2400 --aispmagic 6af23Qtr program.bin

You can use -e option to enable erasing data EEPROM during every programming operation and use -ne to disable this function.


Use -v or -vv to get more or MOAR runtime information.

If you have any questions, please feel free to contact me at laborer(a)


A command line programmer for STC 8051 microcontroller




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