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Can I use a bus control pin as I/O ports when using memory expansion mode?

Latest Updated:01/09/2013

Question:

When using memory expansion mode, can I use a bus control pin as I/O ports?

Answer:

The bus control pins cannot be used as I/O ports in memory expansion mode or microprocessor mode. However, pins not used for bus control can be used as I/O ports in the following situations.

(In the case of the M16C/65C)

  • Pins P1_0 to P1_7 when the data bus width is 8 bits
  • Pins P3_4 to P3_7 and P4_0 to P4_3 when the address bus width is 12 bits
  • Pins P4_0 to P4_3 when the address bus width is 16 bits
  • Unused CSi pins
  • Pins P0_0 to P0_7, P1_0 to P1_7, P3_1 to P3_7, and P4_0 to P4_3 when used as a multiplexed bus

For details for each product, refer to the sections on processor mode and pin function in the product's user's manual: hardware.

Suitable Products
M32C/88
M32C/87
M32C/85
M32C/84
M32C/83
M32C/80
M16C/62A
M16C/62N
M16C/62P
M16C/63
M16C/64
M16C/64A
M16C/64C
M16C/65
M16C/65C
M16C/6C
M16C/6N4, M16C/6N5
M16C/6NK, M16C/6NL, M16C/6NM, M16C/6NN
M16C/30P