Freescale Semiconductor Evaluation Board MPR031/2 for 2- or 3-pad touch sensor controllers DEMOMPR031 DEMOMPR031 データシート
製品コード
DEMOMPR031
MPR03X
Sensors
6
Freescale Semiconductor
2.3.6
Message Format for Writing the MPR03X
A write to the MPR03X comprises the transmission of the MPR03X’s keyscan slave address with the R/W bit set to 0, followed
by at least one byte of information. The first byte of information is the command byte. The command byte determines which
register of the MPR03X is to be written by the next byte, if received. If a STOP condition is detected after the command byte is
received, the MPR03X takes no further action (
by at least one byte of information. The first byte of information is the command byte. The command byte determines which
register of the MPR03X is to be written by the next byte, if received. If a STOP condition is detected after the command byte is
received, the MPR03X takes no further action (
) beyond storing the command byte. Any bytes received after the
command byte are data bytes.
Figure 10. Command Byte Received
Any bytes received after the command byte are data bytes. The first data byte goes into the internal register of the MPR03X
selected by the command byte
selected by the command byte
(Figure 11)
.
Figure 11. Command and Single Data Byte Received
If multiple data bytes are transmitted before a STOP condition is detected, these bytes are generally stored in subsequent
MPR03X internal registers because the command byte address generally auto-increments
MPR03X internal registers because the command byte address generally auto-increments
.
2.3.7
Message Format for Reading the MPR03X
MPR03X is read using MPR03X's internally stored register address as address pointer, the same way the stored register address
is used as address pointer for a write. The pointer generally auto-increments after each data byte is read using the same rules
as for a write
is used as address pointer for a write. The pointer generally auto-increments after each data byte is read using the same rules
as for a write
. Thus, a read is initiated by first configuring MPR03X's register address by performing a write
followed by a repeated start. The master can now read 'n' consecutive bytes from MPR03X, with first data byte being read from
the register addressed by the initialized register address.
the register addressed by the initialized register address.
Figure 12. Reading MPR03X
S
A
A
P
0
SLAVE ADDRESS
COMMAND BYTE
acknowledge from MPR03X
R/W
acknowledge from MPR3X
D15 D14 D13 D12 D11 D10
D9
D8
Command byte is stored on receipt ofSTOP condition
S
A
A
A
P
0
SLAVE ADDRESS
COMMAND BYTE
DATA BYTE
acknowledge from MPR03X
R/W
1 byte
auto-increment memory
word address
D15 D14 D13 D12 D11 D10 D9 D8
D1 D0
D3 D2
D5 D4
D7 D6
Howcommand byte and data byte
map into MPR03X's registers
acknowledge from
MPR03X
acknowledge from
MPR03X
S
A
A P
1
SLAVE ADDRESS
DATA BYTE
R/W
n bytes
auto-increment memory
word address
D1 D0
D3 D2
D5 D4
D7 D6
acknowledge from MPR03X
acknowledge from master
NA