HD404449 Datasheet, PDF (88/123 Pages) Hitachi Semiconductor – HD404449 SERIES

HD404449 Series
Registers for Serial Interface
The serial interface operation is selected, and serial data is read and written by the following registers.
For serial interface 1
• Serial mode register 1A (SM1A: $005)
• Serial mode register 1B (SM1B: $028)
• Serial data register 1
(SR1L: $006, SR1U: $007)
• Port mode register A (PMRA: $004)
• Miscellaneous register (MIS: $00C)
For serial interface 2
• Serial mode register 2A (SM2A: $01B)
• Serial mode register 2B (SM2B: $01C)
• Serial data register 2
(SR2L: $01D, SR2U: $01E)
• Port mode register A (PMRA: $004)
Serial Mode Register 1A (SM1A: $005): This register has the following functions (figure 70).
• R4₁/SCK₁ pin function selection
• Serial interface 1 transmit clock selection
• Serial interface 1 prescaler division ratio selection
• Serial interface 1 initialization
Serial mode register 1A (SM1A: $005) is a 4-bit write-only register. It is reset to $0 by MCU reset.
A write signal input to serial mode register 1A (SM1A: $005) discontinues the input of the transmit clock
to serial data register 1 (SR1L: $006, SR1U: $007) and the octal counter, and the octal counter is reset to
000. Therefore, if a write is performed during data transfer, the serial 1 interrupt request flag (IFS1: $003,
bit 2) is set.
Written data is valid from the second instruction execution cycle after the write operation, so the STS
instruction must be executed at least two cycles after that.
88