SM72442 I2C Register Read Returns 6 Bytes Instead of 7 With Arduino—Why?

The discussion addresses an issue with reading I2C registers from the SM72442 MPPT power management IC using an Arduino. The datasheet specifies 7 bytes per register, but only 6 bytes are received consistently, with the first byte always being 0x07 and subsequent bytes after the sixth returning 0x00, even when requesting more bytes or writing maximum values (0xFF) to registers. The Arduino acts as the I2C master, generating the clock (SCLK) during data reads, but the last byte appears missing or replaced by zeros. Troubleshooting steps include verifying I2C speed (noted that SM72442 supports only 100 kHz), using an oscilloscope to monitor signal integrity and timing, and considering Arduino Wire library behavior where the number of bytes returned may not match the number requested. The problem may relate to the I2C communication protocol nuances, clock pulsing, or library limitations rather than hardware faults. No definitive solution was reached, but suggestions emphasize scope analysis and careful timing and protocol verification.
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