September 24, 1998

EDN's 25th Annual Microprocessor/Microcontroller Directory

Hitachi H8

The register-based H8 series includes the H8/300L and H8/300 8-bit µCs with 16-bit instruction words and 16-bit ALUs and the H8/300H and H8S 16-bit µCs with 32-bit ALUs. Most future development in this family will be along the H8S line. Each series is upward-compatible. The H8 devices have eight general-purpose registers, a program counter, and program-status-word registers. The H8S further adds single-cycle execution of the common standard-logic instructions, a multiply-accumulate (MAC) unit in the H8S/2655 series, and extended-control registers. These registers are not part of a register-banking or third addressing-space scheme.

The 8-bit 300L and 300 chips treat registers as 8 or 16 bits, referencing registers as a set of eight 16-bit registers or 16 8-bit registers. The 300H and H8S registers are accessible as 8, 16, or 32 bits. You can dynamically resize the 8- or 16-bit-wide external datapath.

H8 devices have a fixed instruction word with a supplemental word for additional data and a RISC-like load/store architecture. All CPUs have a unified address space. The address space includes a 128-byte register file to access on-chip peripherals as memory-mapped I/O.

Power management: In sleep mode, CPU operation halts, register and RAM contents remain unchanged, and peripherals continue to function. In standby, CPU and peripheral operations halt, and registers and RAM contents remain unchanged. H8S devices can individually control the operation of each of their peripherals. In addition, the H8/300L series and some of the H8S-series devices support 32-kHz subclock operation but require an external switching circuit.

Special instructions: H8 devices are code-compatible and all share an instruction base with 55 to 69 instructions, mnemonics, and a basic addressing philosophy. Bit-manipulation instructions include set, clear, test, and various logic operations. Math functions include add, subtract, increment, decrement, decimal adjust, multiply, divide, and extend sign; the H8S/2655 series includes a MAC instruction. H8 devices also perform block moves.

Special on-chip peripherals: Depending on the device series, Hitachi offers an LCD drive; a vacuum-fluorescent-display drive for small displays, such as a stereo-system display; a keyboard-interface controller that performs keyboard scan; a DRAM refresh; a DMA controller; and an I²C interface. In addition, several H8 devices come with on-chip, 5 or 12V flash memory.

Development tools: Hitachi and third parties offer development tools. The E3000, E6000, and E7000 emulator development platforms from Hitachi support the various members of the H8/300L, 300, 300H, and H8S/2000 series on SPARC, Hewlett-Packard (www.hp.com), and PC environments. Hitachi also offers evaluation kits for product evaluation, benchmarking, and development. These packages typically include a compiler suite, a development/debugger environment, a development board, and supporting documentation and examples. IAR Systems (www.iar.com), Cygnus (www.cygnus.com), and Green Hills Software (www.ghs.com) offer compiler support. Hewlett-Packard and Orion Instruments (www.yokogawa.com) offer emulators. Data I/O (www.dataio.com), BP Microsystems (www.bpmicro.com), Yamaichi (www.yeu.com), and others provide programmer and socket support.

Second sources: There are no second sources for the H8 series.

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