Product Specs

Table Of Contents
25 RTC Real-time counter
Page
248
SysClk
LFClk
PRESC
COUNTER
START
Figure 55: Timing diagram - JITTER_START-
SysClk
LFClk
PRESC
COUNTER
0x000
START
Figure 56: Timing diagram - JITTER_START+
25.9 Reading the COUNTER register
To read the COUNTER register, the internal <<COUNTER>> value is sampled.
To ensure that the <<COUNTER>> is safely sampled (considering an LFCLK transition may occur during
a read), the CPU and core memory bus are halted for three cycles by lowering the core PREADY signal.
The Read takes the CPU 2 cycles in addition resulting in the COUNTER register read taking a fixed five
PCLK16M clock cycles.
SysClk
PREADY
LFClk
<<COUNTER>>
COUNTER
COUNTER_READ
Figure 57: Timing diagram - COUNTER_READ
25.10 Registers
Table 47: Instances
Base address
Peripheral
Instance
Description
Configuration
0x4000B000
RTC
RTC0
Real-time counter 0
CC[0..2] implemented, CC[3] not
implemented
0x40011000
RTC
RTC1
Real-time counter 1
CC[0..3] implemented
First tick
0x000
X+1
X+2
X+3
>= ~15 us
0 or more SysClk before
X
N-1
N
X
N
375.2 ns
First tick
X+1 X+2
X
<= ~250 us