HD6432670 Hitachi, HD6432670 Datasheet - Page 743

• Manufacturer Part Number: HD6432670
• Description: (HD64F267x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

When turning on the power or switching between Smart Card interface mode and software standby
mode, the following procedures should be followed in order to maintain the clock duty cycle.
Powering On: To secure the clock duty cycle from power-on, the following switching procedure
should be followed.
When changing from smart card interface mode to software standby mode:
When returning to smart card interface mode from software standby mode:
1. The initial state is port input and high impedance. Use a pull-up resistor or pull-down
2. Fix the SCK pin to the specified output level with the CKE1 bit in SCR.
3. Set SMR and SCMR, and switch to smart card mode operation.
4. Set the CKE0 bit in SCR to 1 to start clock output.
1. Set the data register (DR) and data direction register (DDR) corresponding to the SCK pin
2. Write 0 to the TE bit and RE bit in the serial control register (SCR) to halt transmit/receive
3. Write 0 to the CKE0 bit in SCR to halt the clock.
4. Wait for one serial clock period.
5. Make the transition to the software standby state.
1. Exit the software standby state.
2. Write 1 to the CKE0 bit in SCR and output the clock. Signal generation is started with the
resistor to fix the potential.
to the value for the fixed output state in software standby mode.
operation. At the same time, set the CKE1 bit to the value for the fixed output state in
software standby mode.
During this interval, clock output is fixed at the specified level, with the duty cycle
preserved.
normal duty cycle.
[1] [2] [3]
Normal operation
Figure 15.32 Clock Halt and Restart Procedure
[4] [5]
Software
standby
[6]
[7]
Normal operation
Rev. 2.0, 04/02, page 697 of 906