SPRUGR9H November 2010 – April 2015 66AK2E05 , 66AK2H06 , 66AK2H12 , 66AK2H14 , 66AK2L06 , AM5K2E02 , AM5K2E04 , SM320C6678-HIREL , TMS320C6652 , TMS320C6654 , TMS320C6655 , TMS320C6657 , TMS320C6670 , TMS320C6671 , TMS320C6672 , TMS320C6674 , TMS320C6678
The global timer value used by the PDSP may be programmed using the format shown in Table 4-50. This timer has a programmable count based on the sub-system clock. When this count expires, a local tick is registered in the firmware. The tick is used when timing channel interrupts based on the Timer Load Count value supplied in the channel configuration.
Command Buffer Offset | Field | |||
---|---|---|---|---|
Byte 3 | Byte 2 | Byte 1 | Byte 0 | |
0x00 | Return code | 0 | 0x82 | 0 |
0x04 | 0 | Timer Constant |
The value of Timer Constant is the number of queue manager sub-system clocks divided by 2 that comprise a single tick in the accumulator firmware.
For example, if the sub-system clock is 350 MHz (the default), and the desired firmware tick is 20 µs, the proper timer constant for this command is calculated as follows:
Timer constant = (350,000,000 cycles/sec) × (0.000020 sec) / (2 cycles) = 3,500
The firmware initializes with a default timer constant value of 4375 (25 µs at 350Mhz) For devices with other sub-system clock rates, the default timer value will not be correct (at 400Mhz, 25 µs = (400,000,000 × 0.000025) / 2 = 5,000).