SH7055S Datasheet, PDF (663/1002 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

18.4 Operation
18.4.1 H-UDI Interrupt
When an H-UDI interrupt instruction is transferred to SDIR via TDI, an interrupt is generated.
Data transfer can be controlled by means of the H-UDI interrupt service routine. Transfer can be
performed by means of SDDR.
Control of data input/output between an external device and the H-UDI is performed by
monitoring the SDTRF bit in SDSR externally and internally. Internal SDTRF bit monitoring is
carried out by having SDSR read by the CPU.
The H-UDI interrupt and serial transfer procedure is as follows.
1. An instruction is input to SDIR by serial transfer, and an H-UDI interrupt request is generated.
2. After the H-UDI interrupt request is issued, the SDTRF bit in SDSR is monitored externally.
After output of SDTRF = 1 from TDO is observed, serial data is transferred to SDDR.
3. On completion of the serial transfer to SDDR, the SDTRF bit is cleared to 0, and SDDR can be
accessed by the CPU. After SDDR has been accessed, SDDR serial transfer is enabled by
setting the SDTRF bit to 1 in SDSR.
4. Serial data transfer between an external device and the H-UDI can be carried out by constantly
monitoring the SDTRF bit in SDSR externally and internally.
Figures 18.2, 18.3, and 18.4 show the timing of data transfer between an external device and the
H-UDI.
Rev.2.0, 07/03, page 625 of 960