Is there any way to store data in the MLA between frames?

Extensions
1

Is there any way to store data in the MLA between frames?

I’d like to be able to treat the first data byte of an I2C bus specially, and I do not mean the address byte. I use the first data byte to specify the context of later bytes and would like to use a lookup table to define what should be displayed instead of the numerical data itself. My first thought was to just use a bool and change it after it is first accessed, then set it again on the next address frame, but this variable seems to just get deleted after each frame.

# High Level Analyzer
# For more information and documentation, please go to https://support.saleae.com/extensions/high-level-analyzer-extensions

from saleae.analyzers import HighLevelAnalyzer, AnalyzerFrame, StringSetting, NumberSetting, ChoicesSetting


# High level analyzers must subclass the HighLevelAnalyzer class.
class Hla(HighLevelAnalyzer):
    
    START = 0
    # An optional list of types this analyzer produces, providing a way to customize the way frames are displayed in Logic 2.
    result_types = {
        'i2c-address': {
            'format': '{{data.description}}'
        },
        'i2c-data': {
            'format': '{{data.description}}'
        }
    }

    

    def __init__(self):
        pass

    def decode(self, frame: AnalyzerFrame):
        if frame.type == 'address':
            direction = 'Read' if frame.data['read'] else 'Write'
            address = (frame.data['address'][0] << 1) | (1 if frame.data['read'] else 0)
            ack = frame.data['ack']
            START = 1
            return AnalyzerFrame('i2c-address', frame.start_time, frame.end_time, {
                'description': 'Setup {} to {} + {}'.format(direction, 'ALL' if (address == 0) else address, 'ACK' if ack else 'NAK')
            })
        elif frame.type == 'data':
            data = frame.data['data'][0]
            ack = frame.data['ack']
            if START:
                START = 0
                if data == 126:
                    DataText = 'ADDR CHANGE'
                elif data == 5:
                    DataText = 'G1'
                elif data == 9:
                    DataText = 'G6'
                elif data == 4:
                    DataText = 'G92'
                elif data == 6:
                    DataText = 'M202'
                elif data == 8:
                    DataText = 'M204'
                elif data == 7:
                    DataText = 'M205'
                return AnalyzerFrame('i2c-data', frame.start_time, frame.end_time, {'description': '{} + {}'.format(DataText, 'ACK' if ack else 'NAK')})
            else:
                return AnalyzerFrame('i2c-data', frame.start_time, frame.end_time, {'description': '0x{:02X} + {}'.format(data, 'ACK' if ack else 'NAK')})
2

Use your class __init__ to set up member variables. I set up result_types as you have done, but I’d make START a member variable and set it initially in __init__ with

    self.start = 0

then where you use it in your member functions (decode(self, ...) for example) use it the the same way (self.start).