Ecg: Electrical Ma From The Body Surfa; Monitoring Of Heart - STMicroelectronics STM32 Cortex-M3 Manual

Figure 15. Alternative READ Mode Sequence
BUS ACTIVITY:
4.15 Inter IC Bus (I C)
M41T81 MASTER
Figure 10. Serial Bus Data Transfer Sequence
SDA LINE
4. The number of data bits between the start and the stop bit is not limited but has to be a full DATA LINE
STABLE
DATA VALID
byte number (8/16 bit).
M41T81
BUS ACTIVITY:
CLOCK
5. After every data block (8/16 data bit) the receiver pulls the ACK to GND when he has
READ Mode
received the message. The receiver can be the master or the slave (see Figure 4.19)
DATA
In this mode the master reads the M41T81 slave
6. With the stop bit the transfer is quit. Clock is High, Data changes from Low to High.
after setting the slave address (see Figure 14,
START
CONDITION
page 12). Following the WRITE Mode Control Bit
(R/W=0) and the Acknowledge Bit, the word ad-
WRITE Mode
dress 'An' is written to the on-chip address pointer.
Figure 11. Acknowledgement Sequence
In this mode the master transmitter transmits to
Next the START condition and slave address are
the M41T81 slave receiver. Bus protocol is shown repeated followed by the READ Mode Control Bit
START
SCL FROM
(R/W=1). At this point the master transmitter be-
in Figure 16, page 13. Following the START con- 1
MASTER
comes the master receiver. The data byte which
dition and slave address, a logic '0' (R/W=0) is
DATA OUTPUT
MSB
was addressed will be transmitted and the master
BY TRANSMITTER
placed on the bus and indicates to the addressed
receiver will send an Acknowledge Bit to the slave
device that word address "An" will follow and is to
DATA OUTPUT
BY RECEIVER
transmitter. The address pointer is only increment-
be written to the on-chip address pointer. The data
ed on reception of an Acknowledge Clock. The
word to be written to the memory is strobed in next
Figure 4.19: I C ACK Sequence
M41T81 slave transmitter will now place the data
byte at address An+1 on the bus, the master re-
ceiver reads and acknowledges the new byte and
Figure 16. WRITE Mode Sequence
the address pointer is incremented to "An+2."
BUS ACTIVITY:
Figure 13. Slave Address Location
MASTER
SDA LINE
BUS ACTIVITY:
10/28
Figure 14. READ Mode Sequence
BUS ACTIVITY:
MASTER
SDA LINE S
BUS ACTIVITY:
12/28
Lukas Kohler
S
SLAVE
ADDRESS
CHANGE OF STOP
DATA ALLOWED CONDITION
CLOCK PULSE FOR
ACKNOWLEDGEMENT
2 8
LSB
WORD
S
ADDRESS (An)
START
SLAVE
ADDRESS
Figure 4.21: I C writing data from Master to the Slave.
WORD
ADDRESS (An)
SLAVE
ADDRESS
DATA n+X P
Figure 4.22: I C reading data from the Slave
DATA n DATA n+1
This cycle of reading consecutive addresses will
continue until the master receiver sends a STOP
M41T81
condition to the slave transmitter.
Figure 10. Serial Bus Data Transfer Sequence
AI00587
The system-to-user transfer of clock data will be
halted whenever the address being read is a clock
and the internal address pointer is incremented to
address (00h to 07h). The update will resume due
the next address location on the reception of an
to a Stop Condition or when the pointer increments
9 acknowledge clock. The M41T81 slave receiver
CLOCK
to any non-clock address (08h-13h).
will send an acknowledge clock to the master
Note: This is true both in READ Mode and WRITE
transmitter after it has received the slave address
Mode.
DATA
see Figure 13, page 12 and again after it has re-
An alternate READ Mode may also be implement-
ceived the word address and each data byte.
START
ed whereby the master reads the M41T81 slave
AI00601
CONDITION
without first writing to the (volatile) address point-
er. The first address that is read is the last one
Figure 4.20: I C data transfer sequence
stored in the pointer (see Figure 15, page 13).
Figure 11. Acknowledgement Sequence
START
SCL FROM
MASTER
DATA OUTPUT
BY TRANSMITTER
R/W
DATA OUTPUT
DATA n
BY RECEIVER
SLAVE ADDRESS
1 1 0 1 0 0 0
10/28
S
SLAVE
ADDRESS
DATA n+X
2
The Electrocardiogram
DATA LINE
STABLE
DATA VALID
CHANGE OF
DATA ALLOWED
electrodes placed on the l
below.
1 2
MSB
DATA n+1 DATA n+X
A
AI00602
DATA n DATA n+1
Josef Goette
AI00899
P
Electrocardio
AI00895
• Ecg: electrical ma
from the body surfa

• monitoring of heart

STOP
CONDITION
AI00587
The Ecg signal can b
CLOCK PULSE FOR
ACKNOWLEDGEMENT
8 9
LSB
P
AI00601
AI00591
13/28
43