Table of Contents
Advertisement
(4) Synchronization control
Busy control and strobe control are functions to synchronize transmission/reception between the master device
and a slave device.
By using these functions, a shift in bits being transmitted or received can be detected.
(a) Busy control option
www.DataSheet4U.com
CHAPTER 17 SERIAL INTERFACE CHANNEL 1
Busy control is a function to keep the serial transmission/reception by the master device waiting while the
busy signal output by a slave device to the master is active.
When using this busy control option, the following conditions must be satisfied.
• Bit 5 (ATE) of the serial operation mode register 1 (CSIM1) is set to 1.
• Bit 1 (BUSY1) of the automatic data transmission/reception control register (ADTC) is set to 1.
Figure 17-17 shows the system configuration of the master device and a slave device when the busy control
option is used.
Figure 17-17. System Configuration when Busy Control Option Is Used
Master device
µ
( PD78014, 78014Y Subseries)
The master device inputs the busy signal output by the slave device to the BUSY/P24 pin. The master device
samples the input busy signal in synchronization with the falling of the serial clock. Even if the busy signal
becomes active while 8-bit data is being transmitted or received, transmission/reception by the master is
not kept waiting. If the busy signal is active at the rising edge of the serial clock 2 clocks after completion
of transmission/reception of the 8-bit data, the busy input becomes valid. After that, the master transmission/
reception is kept waiting while the busy signal is active.
The active level of the busy signal is set by bit 0 (BUSY0) of ADTC.
BUSY0 = 0: Active high
BUSY0 = 1: Active low
When using the busy control option, select the internal clock as the serial clock. Control with the busy signal
cannot be implemented with the external clock.
Figure 17-18 shows the operation timing when the busy control option is used.
Caution Busy control cannot be used simultaneously with the interval time control function of the
automatic data transmission/reception interval specification register (ADTI). If used,
busy control is invalid.
Slave device
SCK1
SCK1
SO1
SO1
SI1
SI1
BUSY
439
Advertisement
Table of Contents
