HD6417618 RENESAS [Renesas Technology Corp], HD6417618 Datasheet - Page 343

• Manufacturer Part Number: HD6417618
• Description: 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7618 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

(3)
The sample countermeasure for the case of TC interrupt-driven software shown below is the
addition of timeout processing within the limit imposed by the maximum specified time. This is
based on the method explained in (b) Countermeasure by adding timeout processing in section
12.4.1, Usage Notes on SH-Ether EtherC/E-DMAC Status Register (EESR).
The maximum specified time should be set with reference to the maximum times in consideration
of retry processing (table 12.2). From this maximum specified time, determine n, the number of
calls of the OS service routine with a timeout function.
(b) Countermeasure as the addition of timeout processing within the limit imposed by the
1. Prepare multiple transmit descriptors so that multiple frames can be transmitted.
2. After setting the transmit descriptors, start transmission by setting bit 0 (TR) in the E-DMAC
3. Before setting the next frame for transmission in the transmit descriptor (when a transmission
4. If the TACT bit is clear, set the frame for transmission in the corresponding transmit descriptor
Note: Before setting the TR bit in EDTRR, always read the TR bit and make sure that TR = 0.
5. When the transmission task has left the waiting state and entered the execution state within the
6. If the transmission task has not left the waiting state within the specified constant period,
7. If the TACT bit is clear, set the frame for transmission in the corresponding transmit descriptor
maximum specified time
transmit request register (EDTRR).
task arises), check the TACT bit in the transmit descriptor.
and start transmission by setting the TR bit in EDTRR. If the TACT bit is set to 1, set counter i
to 0 (counter i is the variable that indicates the number of calls of the OS service routine with a
timeout function). Then, place the transmission task in a waiting state by calling the OS routine
(e.g. acquire a semaphore that has a timeout limit).
specified constant period, set the frame for transmission in the corresponding transmit
descriptor and then set the TR bit in EDTRR to start transmission. The transmission task
should be taken out of the waiting state by the interrupt handler initiated by generation of the
TC interrupt.
increment counter i. Then, if i < n, check the TACT bit in the corresponding transmit
descriptor. The value for counting, n, is determined by the user with reference to table 12.2.
and set the TR bit in EDTRR to start transmission. If the TACT bit is set to 1, return the
transmission task to the waiting state by calling an OS service routine that has a timeout
function, and then repeat steps 5 and 6.
Countermeasure for the case of TC interrupt-driven software
Section 12 Ethernet Controller Direct Memory Access Controller (E-DMAC)
Rev. 6.00 Jun. 12, 2007 Page 311 of 610
REJ09B0131-0600