Panasonic MN101C00 User Manual

Page 109

Chapter 5 Serial Functions

Synchronous Serial Interface

When the clock source is an external clock (SBT0 pin input):

•

Set the SC0SBTM flag of the SC0MD3 register.

•

Set bit 2 of the P0DIR register to input mode.

•

Set the P0PLU register, if necessary.

(7)

Select the SC0SBOM flag of the SC0MD3 register.

(8)

Select the SC0IOM flag of the SC0MD3 register.

(9)

Select serial communication by setting the SC0SBOS flag of the

SC0MD3 register to "1."

(10)

Set transmit data to serial interface 0 transmit/receive shift register

(SC0TRB). This will start the serial transmission.

(11)

When serial transmission begins, the SC0BSY flag of the SC0CTR register

is set to "1," indicating that a serial transfer is in progress.

(12)

When the serial transmission has completed, the SC0BSY flag of the

SC0CTR register is cleared to "0" and the SC0 transfer complete interrupt

request flag is set to "1." The SC0TRI flag of SC0MD1 register 1 is cleared

to "0."

When the serial port is enabled

and the SC0CE1 to 0 flags of

the SC0MD0 register are

changed, the transfer bit count

in the SC0LNG2 to 0 flags of

the SC0MD0 register may be

incremented.

Enabling the start condition

drives the SBO0 pin high for a

fixed time interval (1/2 the

clock source cycle) after the

transmission is completed. If

the start condition is disabled,

the SBO0 pin will remain at the

value of the of the last data bit.

If the SC0IOM flag of the

SC0MD3 register is set for a

pin connection, the SBI0 pin

can be used as a port. The

SBO0 pin receives data during

the input mode and transmits

data during the output mode.

The SC0LNG2 to 0 flags

change at the opposite edge of

the transmit data output edge.

Serial interface 0 begins

operation when the SC0SBOS

flag or the SC0SBIS flag is set

to "1." Set the SC0SBOS flag

or the SC0SBIS flag after all

conditions have been set.

After the transfer is complete, the transfer bit count in the

SC0LNG2 to 0 flags of the SC0MD0 register will be changed.

Except in an 8-bit transfer, reset the transfer bit count at the

time of the next transmission.

The SC0SBTS flag of the SC0MD3 register must be set to "1"

before the SC0SBOS flag of the SC0MD3 register is set to

"1."

When switching from transmission to reception, set the

SC0SBOS flag of the SC0MD3 register to "0" and then set

the SC0SBIS flag to "1." Do not change both of these flags at

the same time.