Conventional twisted-pair communication cabling with its convenient connectors, and a ‘modular’ I2C-bus system approach, make very large I2C systems such as for solar panel array control or multi-storey car parks to indicate free spaces by overhead red/green indicators, very simple to construct. Because very large numbers of buffers and the wiring will introduce signal delays that can ‘skew’ the timing of the I2C-bus clock and data signals, it becomes necessary to modify the timing margins generated by the conventional I2C-bus components used in small systems. This application note describes two timing delay modules that ensure all devices in a very large system will still receive compliant I2C-bus timing signals.