Editing IrDA (section)

===Power meters===
Many modern (2021) implementations are used for semi-automated reading of power meters. This high-volume application is keeping IrDA transceivers in production. Lacking specialized electronics, many power meter implementations utilize a bit-banged SIR phy, running at 9600 BAUD using a minimum-width pulse (i.e. 3/16 of a 115.2KBAUD pulse) to save energy. To drive the LED, a computer-controlled pin is turned on and off at the right time. Cross-talk from the LED to the receiving [[PIN diode]] is extreme, so the protocol is [[half-duplex]]. To receive, an external interrupt bit is started by the start bit, then polled a half-bit time after following bits. A timer interrupt is often used to free the CPU between pulses. Power meters' higher protocol levels abandon IrDA standards, typically using [[IEC 62056|DLMS/COSEM]] instead. With IrDA transceivers (a package combining an IR LED and PIN diode), even this crude IrDA SIR is extremely resistant to external optical noise from incandescents, sunlight, etc.