Embedded systems frequently use HD44780-type LCD displays as it is considered the most popular alphanumeric display controller. The interface comprises at least 14 pins: eight for data, three for control (EN, WR, RS), two for power supply (Vdd, Vss), and one for contrast (Vre). Configured in 8-bit mode, it requires at least 10 I/O lines (D0..D7, EN, RS). Configured in 4-bit mode, it requires at least six I/O lines (D4..D7, EN, RS). This last case seems usable when using an 8-pin PICmicro. However, 8-pin PICmicros have one pin as an input-only pin.
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