stcgal is a command line flash programming tool for STC MCU Ltd. [1] 8051 compatible microcontrollers. The name was inspired by avrdude [2].

STC microcontrollers have an UART/USB based boot strap loader (BSL). It utilizes a packet-based protocol to flash the code memory and IAP memory over a serial link. This is referred to as in-system programming (ISP). The BSL is also used to configure various (fuse-like) device options. Unfortunately, this protocol is not publicly documented and STC only provide a (crude) Windows GUI application for programming.

stcgal is a full-featured Open Source replacement for STC's Windows software; it supports a wide range of MCUs, it is very portable and suitable for automation.

[1] http://stcmcu.com/ [2] http://www.nongnu.org/avrdude/

stcgal should fully support STC 89/90/10/11/12/15 series MCUs.

So far, stcgal was tested with the following MCU models:

• STC89C52RC (BSL version: 4.3C/6.6C)
• STC90C52RC (BSL version: 4.3C)
• STC89C54RD+ (BSL version: 4.3C)
• STC12C2052 (BSL version: 5.8D)
• STC12C2052AD (BSL version: 5.8D)
• STC12C5608AD (BSL version: 6.0G)
• STC12C5A16S2 (BSL version: 6.2I)
• STC12C5A60S2 (BSL version: 6.2I/7.1I)
• STC11F02E (BSL version: 6.5K)
• STC10F04XE (BSL version: 6.5J)
• STC11F08XE (BSL version: 6.5M)
• STC12C5204AD (BSL version: 6.6H)
• STC15F104E (BSL version: 6.7Q)
• STC15F204EA (BSL version: 6.7R)
• STC15L104W (BSL version: 7.1.4Q)
• STC15F104W (BSL version: 7.1.4Q)
• IAP15F2K61S2 (BSL version: 7.1.4S)
• STC15L2K16S2 (BSL version: 7.2.4S)
• STC15W408AS (BSL version: 7.2.4T)
• STC15W4K56S4 (BSL version: 7.3.4T, UART and USB mode)

Compatibility reports, both negative and positive, are welcome.

• UART and USB BSL support
• Display part info
• Determine operating frequency
• Program flash memory
• Program IAP/EEPROM
• Set device options
• Read unique device ID (STC 10/11/12/15)
• Trim RC oscillator frequency (STC 15)
• Automatic power-cycling with DTR toggle
• Automatic UART protocol detection

stcgal requires Python 3.2 (or later) and pySerial. USB support is optional and requires pyusb 1.0.0b2 or later. You can run stcgal directly with the included stcgal.py script. The recommended method for permanent installation is to use Python's setuptools. Run ./setup.py build to build and sudo ./setup.py install to install stcgal. A permanent installation provides the stcgal command.

Call stcgal with -h for usage information.

usage: stcgal.py [-h] [-a] [-P {stc89,stc12a,stc12,stc15a,stc15,auto}]
                 [-p PORT] [-b BAUD] [-l HANDSHAKE] [-o OPTION] [-t TRIM] [-D]
                 [code_image] [eeprom_image]

stcgal 1.0 - an STC MCU ISP flash tool
(C) 2014-2015 Grigori Goronzy
https://github.com/grigorig/stcgal

positional arguments:
  code_image            code segment file to flash (BIN/HEX)
  eeprom_image          eeprom segment file to flash (BIN/HEX)

optional arguments:
  -h, --help            show this help message and exit
  -a, --autoreset       cycle power automatically by asserting DTR
  -P {stc89,stc12a,stc12,stc15a,stc15,auto}, --protocol {stc89,stc12a,stc12,stc15a,stc15,auto}
                        protocol version
  -p PORT, --port PORT  serial port device
  -b BAUD, --baud BAUD  transfer baud rate (default: 19200)
  -l HANDSHAKE, --handshake HANDSHAKE
                        handshake baud rate (default: 2400)
  -o OPTION, --option OPTION
                        set option (can be used multiple times)
  -t TRIM, --trim TRIM  RC oscillator frequency in kHz (STC15 series only)
  -D, --debug           enable debug output

Most importantly, -p sets the serial port to be used for programming.

STC MCUs use a variety of related but incompatible protocols for the BSL. The protocol can be specified with the -P flag. By default UART protocol autodetection is used. The mapping between protocols and MCU series is as follows:

• stc89 STC89/90 series
• stc12a STC12x052 series and possibly others
• stc12b STC12x52 series, STC12x56 series and possibly others
• stc12 Most STC10/11/12 series
• stc15a STC15x104E and STC15x204E(A) series
• stc15 Most STC15 series
• usb15 USB support on STC15W4 series
• auto Automatic detection of UART based protocols (default)

The text files in the doc/ subdirectory provide an overview over the reverse engineered protocols used by the BSLs. For more details, please read the source code.

Call stcgal without any file to program. It will dump information about the MCU, e.g.:

$ ./stcgal.py -P stc15
Waiting for MCU, please cycle power: done
Target model:
  Name: IAP15F2K61S2
  Magic: F449
  Code flash: 61.0 KB
  EEPROM flash: 0.0 KB
Target frequency: 10.046 MHz
Target BSL version: 7.1S
Target wakeup frequency: 34.771 KHz
Target options:
  reset_pin_enabled=False
  clock_source=internal
  clock_gain=high
  watchdog_por_enabled=False
  watchdog_stop_idle=True
  watchdog_prescale=256
  low_voltage_reset=True
  low_voltage_threshold=3
  eeprom_lvd_inhibit=True
  eeprom_erase_enabled=False
  bsl_pindetect_enabled=False
  por_reset_delay=long
  rstout_por_state=high
  uart2_passthrough=False
  uart2_pin_mode=normal
Disconnected!

stcgal supports Intel HEX encoded files as well as binary files. Intel HEX is autodetected by file extension (.hex, .ihx or .ihex).

Call stcgal just like before, but provide the path to the code image:

$ ./stcgal.py -P stc15 hello.hex
Waiting for MCU, please cycle power: done
Target model:
  Name: IAP15F2K61S2
  Magic: F449
  Code flash: 61.0 KB
  EEPROM flash: 0.0 KB
Target frequency: 10.046 MHz
Target BSL version: 7.1S
Target wakeup frequency: 34.771 KHz
Target options:
  reset_pin_enabled=False
  clock_source=internal
  clock_gain=high
  watchdog_por_enabled=False
  watchdog_stop_idle=True
  watchdog_prescale=256
  low_voltage_reset=True
  low_voltage_threshold=3
  eeprom_lvd_inhibit=True
  eeprom_erase_enabled=False
  bsl_pindetect_enabled=False
  por_reset_delay=long
  rstout_por_state=high
  uart2_passthrough=False
  uart2_pin_mode=normal
Loading flash: 80 bytes (Intel HEX)
Trimming frequency: 10.046 MHz
Switching to 19200 baud: done
Erasing flash: done
Writing 256 bytes: .... done
Setting options: done
Target UID: 0D000021022632
Disconnected!

You can also program the EEPROM part of the memory, if applicable. Add the EEPROM image path to the commandline after the flash image path.

stcgal uses a conservative baud rate of 19200 bps by default. Programming can be sped up by choosing a faster baud rate with the flag -b.

stcgal dumps a number of target options. These can be modified as well. Provide one (or more) -o flags followed by a key-value pair on the commandline to adjust these settings. For instance, you can enable the external crystal as clock source:

$ ./stcgal.py -P stc15 -o clock_source=external hello.bin

Please note that device options can only be set when flash memory is programmed!

Not all parts support all options. The protocols or parts that support each option are listed in the description.

If the internal RC oscillator is used (clock_source=internal), stcgal can execute a trim procedure to adjust it to a given value. This is only supported by STC15 series. The trim values are stored with device options. Use the -t flag to request trimming to a certain value. Generally, frequencies between 4 and 35 MHz can be achieved. If trimming fails, stcgal will abort.

STC's microcontrollers require a power-on reset to invoke the bootloader, which can be inconvenient. stcgal can use the DTR control signal of a serial interface to automate this. The DTR signal is asserted for approximately 500 ms when the autoreset feature is enabled with the -a flag. This requires external circuitry to actually switch the power. In some cases, when the microcontroller draws only little power, it is possible to directly supply power from the DTR signal, however.

The exit status is 0 if no error occured while executing stcgal. Any error, such as a protocol error or I/O error, results in an exit status of 1. If the the user aborted stcgal by pressing CTRL-C, that results in an exit status of 2.

STC15W4 series have an USB-based BSL that can be optionally used. USB support in stcgal is experimental and might change in the future. USB mode is enabled by using the usb15 protocol. The port (-p) flag as well as the baudrate options are ignored for the USB protocol. RC frequency trimming is not supported.

stcgal is published under the MIT license.