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Renesas Brasil - Knowledgebase

If 16 bit bus with is selected, is 8 bit bus width selectable using ABWCR?

Latest Updated:04/07/2011


In Section 9 (BSC)/Features, it says "8-bit access or 16-bit access can be selected for each area" but for the bus width controller register (ABWCR), it says "If any area is designed as 16-bit access space, 16-bit bus mode is set".
If 16-bit bus width is selected, is 8-bit bus width selectable?


Yes. You can select 8-bit access area/16-bit access area by area, for example selecting 8-bit bus width for one area and 16-bit bus width for another area.
However, if there is a 16-bit bus width in any external bus area, the data bus will require 16 bits, so even when accessing to an 8-bit bus width area, the remaining 8-bit bus pins cannot be used as I/O ports.
Suitable Products
H8S Family
H8SX Family