34.9.2.3 Signal Multiplexing
Depending on the Byte Access Type (BAT), only the write signals or the byte select signals are used. To save IOs at the external bus interface, control signals at the SMC interface are multiplexed. The table below shows signal multiplexing depending on the data bus width and the byte access type.
| Signal Name | 32-bit Bus | 16-bit Bus | 8-bit Bus | |||
|---|---|---|---|---|---|---|
| Device Type | 1 x 32-bit | 2 x 16-bit | 4 x 8-bit | 1 x 16-bit | 2 x 8-bit | 1 x 8-bit |
| Byte Access Type (BAT) | Byte Select | Byte Select | Byte Write | Byte Select | Byte Write | – |
| NBS0_A0 | NBS0 | NBS0 | – | NBS0 | – | A0 |
| NWE_NWR0 | NWE | NWE | NWR0 | NWE | NWR0 | NWE |
| NBS1_NWR1 | NBS1 | NBS1 | NWR1 | NBS1 | NWR1 | – |
| NBS2_NWR2_A1 | NBS2 | NBS2 | NWR2 | A1 | A1 | A1 |
| NBS3_NWR3 | NBS3 | NBS3 | NWR3 | – | – | – |
For 32-bit devices, bits A0 and A1 are unused. For 16-bit devices, bit A0 of address is unused. When the Byte Select option is selected, NWR1 to NWR3 are unused. When the Byte Write option is selected, NBS0 to NBS3 are unused.
