ST STM32F40 Series User Manual

Ethernet (ETH): media access control (MAC) with DMA controller RM0090
1003/1422 Doc ID 018909 Rev 4
Ethernet PTP PPS control register (ETH_PTPPPSCR)
Address offset: 0x072C
Reset value: 0x0000 0000
This register controls the frequency of the PPS output.
29.8.4 DMA register description
This section defines the bits for each DMA register. Non-32 bit accesses are allowed as long
as the address is word-aligned.
Ethernet DMA bus mode register (ETH_DMABMR)
Address offset: 0x1000
Reset value: 0x0000 2101
The bus mode register establishes the bus operating modes for the DMA.
Bit 1 TSTTR: Time stamp target time reached
When set, this bit indicates that the value of the system time is greater than or equal to the
value specified in the Target time high and low registers
Bit 0 TSSO: Time stamp second overflow
When set, this bit indicates that the second value of the time stamp has overflowed beyond
0xFFFF FFFF.
313029282726252423222120191817161514131211109876543210
Reserved
TSTTR
TSSO
ro ro
Bits 31:4 Reserved, must be kept at reset value.
Bits 3:0 PPSFREQ: PPS frequency selection
The PPS output frequency is set to 2
PPSFREQ
Hz.
0000: 1 Hz with a pulse width of 125 ms for binary rollover and, of 100 ms for digital rollover
0001: 2 Hz with 50% duty cycle for binary rollover (digital rollover not recommended)
0010: 4 Hz with 50% duty cycle for binary rollover (digital rollover not recommended)
0011: 8 Hz with 50% duty cycle for binary rollover (digital rollover not recommended)
0100: 16 Hz with 50% duty cycle for binary rollover (digital rollover not recommended)
...
1111: 32768 Hz with 50% duty cycle for binary rollover (digital rollover not recommended)
Note: If digital rollover is used (TSSSR=1, bit 9 in ETH_PTPTSCR), it is recommended not to
use the PPS output with a frequency other than 1 Hz. Otherwise, with digital rollover,
the PPS output has irregular waveforms at higher frequencies (though its average
frequency will always be correct during any one-second window).
313029282726252423222120191817161514131211109876543210
Reserved
MB
AAB
FPM
USP
RDP
FB
PM PBL
EDFE
DSL
DA
SR
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rs

ST STM32F40 Series Specifications

General

Brand	ST
Model	STM32F40 Series
Category	Microcontrollers
Language	English