Data Sheet - Freescale Semiconductor

4.3.2 DSI3 Periodic Data Collection Mode response transmission
When Periodic Data Collection Mode is enabled and the device receives either a Broadcast Read or Background Diagnostic
Mode command, the device will respond with periodic data as shown in Figure 45 and described in the following sections.
BUS_I
Response
Current
Command
Block
Slave A Slave B
Slave C
PDCM_RSPST[11:0] on Slave A device
PDCM_RSPST[11:0] on Slave B device
t CmdBlock_ST_PDCM
PDCM_RSPST[11:0] on Slave C device
Figure 45. Periodic Data Collection Mode response transmission
4.3.2.1 Symbol encoding
The symbol encoding used for Periodic Data Collection Mode responses is the same as for Command and Response Mode
responses, and described in Section 4.2.2.1.
4.3.2.2 Response message format
The Periodic Data Collection Mode response format is shown in Table 63.
Table 63. Periodic Data Collection Mode - response format
tPER_PDCM tCmdBlock_PDCM Source ID Keep Alive Counter Status Acceleration Data CRC
SOURCID[3:0] KAC[1:0] S[x:0] D[x:0] CRC[7:0]
Table 64. Periodic Data Collection Mode Response field definitions
Command blocking time is independently
programmed in each slave.
Field Length (Bits) Definition
SOURCID[3:0] 4 Transmits the least significant 4 bits of the SOURCEID register
Transmits the value of a 2-bit rolling counter. The counter is incremented each time a valid Broadcast Read
KAC[1:0] 2 Command is received or a valid Background Diagnostic Mode command is received. The counter does
not increment for Command and Response Mode commands or for invalid commands.
S[3:0]
STATLEN = 0: 4
STATLEN = 1: 0
Reference Table 65.
D[x:0]
DATALEN = 0: 10
DATALEN = 1, 14
Transmits the value in the ACC1_D[15:0] registers as defined in Section 3.1.15.1.
CRC[7:0] 8 Transmits an 8-bit CRC as defined in Section 4.3.2.3
MMA27XXW
Sensors
Freescale Semiconductor, Inc. 73