Procedure For Setting A Register - Fujitsu FR60 Hardware Manual

CHAPTER 4 EXTERNAL BUS INTERFACE
4.10

Procedure for Setting a Register

Observe the following rules when setting the external bus interface:
■ Procedure for Setting the External Bus Interface
1. Before rewriting the contents of a register, be sure to set the CSER register so that the corresponding
area is not used (0). If you change the settings while "1" is set, access before and after the change
cannot be guaranteed.
2. Use the following procedure to change a register:
1) Set "0" for the CSER bit corresponding to the applicable area.
2) Set both ASR and ACR at the same time using word access. When accessing ASR and ACR using
half word, please set ACR after setting ASR.
3) Set AWR.
4) Set the CSER bit corresponding to the applicable area.
3. The CS0 area is enabled after a reset is released. If the area is used as a program area, the register
contents need to be rewritten while the CSER bit is "1". In this case, make the settings described in 2) to
3) above in the initial state with a low-speed internal clock. Then, switch the clock to a high-speed
clock.
4. Use the following procedure to change the register value in an area for which prefetch is enabled:
1) Set "0" for the bit of CSER corresponding to the applicable area.
2) Set "1" for both the PSUS bit and PCLR bit of the TCR register.
3) Set both ASR and ACR at the same time using word access.
4) Set AWR.
5) Set "0" for both the PSUS bit and PCLR bit of the TCR register.
6) Set "1" for the bit of CSER corresponding to the applicable area.
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