Posted on November 16, 2015 at 07:49http://www.st.com/web/en/catalog/tools/FM147/CL1794/SC961/SS1743/PF257871?s_searchtype=keyword
I am confused about ''addend register'' value calculation.
From reference manual:
addend = 2^32 / FreqDivisionRatio;
FreqDivisionRatio = HCLK / 50000000; //50MHz
From PTP demonstraion for STM32F107
(http://www.st.com/web/en/catalog/tools/FM147/CL1794/SC961/SS1743/PF257871?s_searchtype=keyword♯)
Addend = 2^63 / SysClk / Increment
ethernetif.h:
...
/* Examples of subsecond increment and addend values using SysClk = 72 MHz
Addend * Increment = 2^63 / SysClk
ptp_tick = Increment * 10^9 / 2^31
+-----------+-----------+------------+
| ptp tick | Increment | Addend |
+-----------+-----------+------------+
| 119 ns | 255 | 0x1DF170C7 |
| 100 ns | 215 | 0x238391AA |
| 50 ns | 107 | 0x475C1B20 |
| 20 ns | 43 | 0xB191D856 |
| 14 ns | 30 | 0xFE843E9E |
+-----------+-----------+------------+
*/
&sharpdefine ADJ_FREQ_BASE_ADDEND 0xB191D856
&sharpdefine ADJ_FREQ_BASE_INCREMENT 43
...
Which formula is right?
#ptp-ptpd-stm32f107
