SN8P275X Series
8-bit micro-controller build-in 12-bit ADC
SONiX TECHNOLOGY CO., LTD
Page 127
Version 0.7
10.7.5 Slave Wake up
When MCU enter Power down mode, if MSBENB bit is still set, MCU can wake-up by matched device address.
The address of MSP bus following START bit, 8-byte address will shift into MSPSR, if address matched, an NOT
Acknowledge will response on the ninth clock of SCL and MCU will be wake-up, MSPWKset and start wake-up
procedure but MSPIRQ will not set and MSPSR data will not load to MSPUBF. After MCU finish wake-up procedure,
MSP will be in idle status and waiting master’s START signal. Control register BF, MSPIRQ, MSPOV and MSPBUF will
be the same status/data before power down.
If address not matches, a NOT acknowledge is still sent on the ninth clock of SCL, but MCU will be NOT wake-up and
still keep in power down mode.
S
Receiving Address
1
A7
2
A6
3
A5
4
A4
5
A3
6
A2
7
A1
8
9
ACK_
P
SDA
SCL
MSPIRQ
BF
R/W
“
0
"
“
0
"
Wake-up
“
0
"
MSPWK
“
0
"
MCU
Mode
Clear MSPWK,
Set FCPUM0
(Power Down)
Normal Mode
Power down mode
MSP Wake-up Timing Diagram: Address NOT Matched
MSP Wake-up Timing Diagram: Address Matched
Note: 1. MSP function only can work on Normal mode, when wake-up from power down mode, MCU must
operate in Normal mode before Master sent START signal.
Note:2. In MSP wake-up, if the address not match, MCU will keep in power down mode.
Note 3. Clear MSPWK before enter power down mode by Software for wake-up indication.