stcgal - STC MCU flash tool

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 a UART based boot strap loader (BSL). It utilizes a packet-based protocol to flash the code memory and IAP memory. 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 replacement for STC's Windows software; it is very portable and suitable for automation.

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

Supported MCU models

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)
• STC12C2052AD (BSL version: 5.8D)
• STC12C5A60S2 (BSL version: 6.2I)
• STC11F08XE (BSL version: 6.5M)
• STC15F104E (BSL version: 6.7Q)
• STC15F204EA (BSL version: 6.7R)
• STC15L104W (BSL version: 7.1Q)
• IAP15F2K61S2 (BSL version: 7.1S)

More compatibility testing is going to happen soon.

Features

• Display part info
• Program flash memory
• Program IAP/EEPROM
• Set device options
• Read unique device ID (STC 10/11/12/15)
• Trim RC oscillator frequency (STC 15)

Installation

stcgal requires Python 3.2 (or later) and pySerial. 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.

Usage

See stcgal.py -h for usage information.

$ ./stcgal.py -h
usage: stcgal.py [-h] [-P {stc89,stc12a,stc12,stc15a,stc15}] [-p PORT]
                 [-b BAUD] [-l HANDSHAKE] [-o OPTION] [-t TRIM] [-D]
                 [code_binary] [eeprom_binary]

stcgal - an STC MCU ISP flash tool

positional arguments:
  code_binary           code segment binary file to flash
  eeprom_binary         eeprom segment binary file to flash

optional arguments:
  -h, --help            show this help message and exit
  -P {stc89,stc12a,stc12,stc15a,stc15}, --protocol {stc89,stc12a,stc12,stc15a,stc15}
                        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.

Protocols

STC MCUs use a variety of related but incompatible protocols for the BSL. The protocol must be specified with the -P flag. Here's the general mapping between protocols and MCU series:

• stc89 STC 89/90 series
• stc12a STC12Cx052AD and possibly others
• stc12 Most STC10/11/12 series
• stc15a STC15x104E and STC15x204E(A) series
• stc15 Most STC15 series

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.

Getting MCU information

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: 11.054 MHz
Target BSL version: 7.1S
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
  power_on_reset_delay=long
  rstout_por_state=high
  uart_passthrough=False
  uart_pin_mode=normal
Disconnected!

Program the flash memory

Please note that stcgal only handles raw binary encoded files at this point. You can easily convert common Intel HEX files with objcopy -I ihex -O binary input.hex output.bin.

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

$ ./stcgal.py -P stc15 hello.bin
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: 11.054 MHz
Target BSL version: 7.1S
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
  power_on_reset_delay=long
  rstout_por_state=high
  uart_passthrough=False
  uart_pin_mode=normal
Trimming frequency: 11.104 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 binary to the commandline after the code binary.

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.

Device options

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!

Option keys

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

Option key	Possible values	Description
cpu_6t_enabled	true/false	6T fast mode (STC89 only)
bsl_pindetect_enabled	true/false	BSL only enabled when P3.2/P3.3 or P1.0/P1.1 (depends on model) are low
eeprom_erase_enabled	true/false	Erase EEPROM with next programming cycle
clock_gain	low/high	Clock gain for external crystal
ale_enabled	true/false	ALE pin enabled if true, normal GPIO if false (STC89 only)
xram_enabled	true/false	Use internal XRAM (STC89 only)
watchdog_por_enabled	true/false	Watchdog after power-on reset (POR)
low_voltage_detect	true/false	Low-voltage detection (brownout) (STC12A+)
clock_source	internal/external	Use internal (RC) or external (crystal) clock (STC12A+, not on all models)
watchdog_stop_idle	true/false	Stop watchdog in IDLE mode (STC12A+)
watchdog_prescale	2,4,8,...,256	Watchdog timer prescaler. Must be a power of two. (STC12A+)
reset_pin_enabled	true/false	RESET pin enabled if true, normal GPIO if false (STC12+)
oscillator_stable_delay	4096,...,32768	Crystal stabilization delay in clocks. Must be a power of two. (STC11F series only)
por_reset_delay	short/long	Power-on reset (POR) delay (STC12+)
low_voltage_threshold	0...7	Low-voltage detection threshold. Model specific. (STC15A+)
eeprom_lvd_inhibit	true/false	Ignore EEPROM writes in low-voltage situations (STC15A+)
rstout_por_state	low/high	RSTOUT pin state after power-on reset (STC15)
uart2_passthrough	true/false	Pass-through UART1 to UART2 pins (for single-wire UART mode) (STC15)
uart2_pin_mode	push-pull/normal	Output mode of UART2 TX pin (STC15)

Frequency trimming

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.

License

stcgal is published under the MIT license.