Technical information

CSI to SPI Peripheral Communication in V850ES Microcontrollers

Figure 18. CSI00_ReceiveData(*rxbuf, rxnum): Prepare To Receive Data on CSI00

Return

CSI00_RX_LEN = rxnum

CSI00_RX_CNT = 0

CSI00_RX_ADDRESS = rxbuf

CSI00_RX_LEN = rxnum

CSI00_RX_CNT = 0

CSI00_RX_ADDRESS = rxbuf

2.6.9 MD_INTCSI00() : Interrupt Service Routine for INTCSI00

The MD_INTCSI00() routine is the interrupt service routine for the INTCSI00 interrupt, which

occurs after a byte of data has been transmitted by the CSI00 peripheral. The routine handles

transmission of the next byte, optional storing of received data, and setting flags to notify the main

program of send or receive complete.

The routine first checks if CSI00_TX_CNT (count of bytes sent) is equal to CSI00_TX_LEN

(number of bytes to send). If so, the last byte has been sent, and the callback routine

CALL_CSI00_Send() is called. This routine sets the flag CSI00_SendDone to TRUE.

If the send count is less than the number to send, then additional data needs to be sent. The next

byte to send, pointed to by CSI00_TX_ADDRESS, is written to the SOTB0L register for

transmission; CSI00_TX_ADDRESS is incremented to point to the next byte, and

CSI00_TX_CNT is incremented.

When a byte of data is transmitted by being shifted out on the SO output, a separate byte is

simultaneously received by shifting data in on the SI input. After a byte has been sent, the received

byte is available in the SIRB0L register and in the SI000 serial shift register. Once another byte

has begun transmitting, the SI000 serial shift register may no longer contain the previous data, but

it is still available in the SIRB0L register.

The MD_INTCSI00() routine checks if data should be received by checking for CSI00_RX_LEN

being non-zero. If CSI00_ReceiveData() has been called with an non-zero rxnum parameter, this

will be the case. The routine then checks to see if CSI00_RX_CNT plus one is less than

CSI00_RX_LEN, which will be true for bytes 0 through n-1 of an n-byte receive. If this is the

case, data is read from the SIRB0L register, and stored at the location pointed to by

CSI00_RX_ADDRESS. The address and count are then incremented.

If the count plus one is not less than the length, this is the last byte to receive, and the data is read

directly from the SI000 register, stored at the address, and the count is incremented. The callback

routine CALL_CSI00_Receive() is called, which sets the CSI00_ReceiveDone flag.