1 Intro
2
Electrocardiogram (
Ecg
) Signals
The Electrocardiogram (
Ecg
)
•
Ecg
: electrical manifestation of heart activity recorded
from the body surface
•
monitoring of heart rate
The
Ecg
signal can be recorded fairly easily with surface
electrodes placed on the limbs and/or the chest, see pages
6
–
16
below.
Josef Goette
2
2009
4 Peripherals
Note that the inputs form PA0, PB0, .. PG0 are mapped together to EXTI0. The same is the issue
for all the inputs with the same number.
4.11 Watchdog
b
iwdg
F
Shows how the watchdog is configurated.
4.11.1 Configuration
Select the timeout time in the configuration wizard. During this time your program has to clear
the watchdog by loading a specific value into
IWDG
7→
KR
. If this desn’t happen the watchdog will
reset the CPU.
Figure 4.12:
Watchdog Configuration Wizard
4.12 Real Time Clock (RTC)
b
rtc1
F
RTC is configured to generate a second and an alarm interrupt which turns a LED on.
b
rtc2
F
24h clock, time is sent over the serial interface to its host (115200Baud).
b
rtc3
F
rtc2
including resetting of the RTC when a button is pressed.
The RTC provides a stable clock for the processor. It is able to generate a second interrupt which
gets called every second. An alarm can be set to a specific time. Is this time up an interrupt is gen-
erated. An overflow interrupt occurs when the 32-bit RTC counter overflows. Unfortunately the
RTC doesn’t offer registers for time and date, only for the time in seconds in the two 16-bit register
RTC CNTH (higher 16-bits) and RTC CNTL (lower 16-bits). The alarm registers (RTC ALRH and
RTC ALRL) is similar to the time register.
Figure 4.13:
RTC Configuration Wizard
36
STM32 Cortex-M3 Tutorial
