how to configure the output of PTP_PPS on ADSP-BF518 chip

Hi

I have a question about the IEEE 1588 PTP ENGINE within ADSP-BF518F16 chip when I configure the output of the PTP_PPS.I have program the EMAC_PTP_PPS_STARTHI,EMAC_PTP_PPS_STARTLO and EMAC_PTP_PPS_PERIOD according to the ADSP-BF51x Blackfin Processor Hardware Reference.But when I connect the PG[12] pin on bf518 chip to oscilloscope,I can not observe the signal.So I think it should be the configuration of the registers not proper.I want to know how configure the registers to enable the output of PPS.

Here is my program (SCLK=80MHz,PTP clock=50MHz):

u32 reg_value;

*pEMAC_PTP_PPS_PERIOD = 50000000; /* PTP_CLOCK 50MHz,so 50M cycles is 1s */

*pEMAC_PTP_PPS_STARTLO = 50000000;

*pEMAC_PTP_PPS_STARTHI = 0;

reg_value = 0x0042; /* Default value of PTP_CTL */

reg_value |= 1<<7; /* Enable PPS */

reg_value &= ~(1<<8); /* Enable EtherType mask */

reg_value &= ~(1<<12); /* Enable Control Field Mask */

reg_value &= 1<<9; /* enable IPVM */

reg_value &= 1<<10; /* enable IPTM */

reg_value &= 1<<11; /* enable UDPEM */

reg_value |= 1<<13; /* Enable Clkout */

reg_value |= 1<<1; /* Enable timestamp */

reg_value |= 1<<0; /* Enable the module */

*pEMAC_PTP_CTL = reg_value;

ssync();

Thanks sincere.

charles

Audio Signal Processors

adsp-bf518

ADSP-BF518F16

Blackfin Embedded Processors