CHAPTER 19 IEBus CONTROLLER (V850/SB2)
User’s Manual U13850EJ4V0UM
483
(1) Slave reception processing
If a slave reception request is confirmed during vector interrupt processing, the data transfer direction of
macro service must change from RAM (memory) ‘ SFR (peripheral) to SFR (peripheral) ‘ RAM (memory) until
the first data is received. The maximum pending period of this data transfer direction changing processing is
about 1040
µ
s in communication mode 1.
(2) Interrupt (INTIE1) occurrence
If NACK is received from the slave in the data field, an interrupt (INTIE1) is not issued to the CPU, and the
same data is retransmitted by hardware.
If the transmit data is not written in time during the period of writing the next data, a communication error
interrupt occurs due to occurrence of underrun, and communication ends midway.
(3) Recommunication processing
The vector interrupt processing in <2> judges whether the data has been correctly transmitted within one
frame. If the data has not been correctly transmitted (if the number of data to be transmitted in one frame
could not be transmitted), the data must be retransmitted in the next frame, or the remainder of the data must
be transmitted.