MT9M114_16 Datasheet, PDF (43/62 Pages) ON Semiconductor – High-Definition (HD) System-On- A-Chip (SOC) Digital Image Sensor

MT9M114: 1/6-Inch 720p High-Definition (HD) System-On-A-Chip (SOC) Dig-
ital Image Sensor
Figure 28: Normal Use of SADDR
R0x002E
(USER_DEFINED_DEVICE_ADDRESS_ID)
ID0 (Default: 0x90)
ID1 (Default: 0xBA)
slave Device
ID
SADDR
There is a single register to control this function, named CHAIN_CONTROL (R0x31FC).
This register is controlled by the host. The register field assignment is shown in Table 16.
Table 16:
Bit
15
14
13
12
11:8
7:0
CHAIN_CONTROL Register
Name
chain_enable
sync_enable
master
RESERVED
position
RESERVED
Default Description
0: multi-camera daisy-chain communication function is disabled.
0
1: multi-camera daisy-chain communication function is enabled.
The result of toggling this bit while the sensor is streaming is UNDEFINED.
0: multi_sync function is disabled.
0
1: multi-sync function is enabled.
The result of toggling this bit while the sensor is streaming is UNDEFINED.
0: this node is not the master.
0
1: this node is the master.
The result of toggling this bit while the sensor is streaming is UNDEFINED.
A unique value assigned to each device in the daisy-chain. The device furthest from the
0
master is assigned a position value of 0. The next device is assigned a position value of 1.
For N devices in a daisy-chain, the master is assigned a position value of N-1.
The result of toggling this bit while the sensor is streaming is UNDEFINED.
Configuration
Before the multi-sync function can be used, each MT9M114 in the daisy-chain must be
configured. This process is performed by the host with no involvement from MT9M114
firmware. Configuration involves assigning a unique slave address to each MT9M114
and configuring the CHAIN_CONTROL register on each MT9M114.
After reset (before configuration) the master MT9M114 has its SADDR input wired to '0'
and all other MT9M114 in the daisy-chain have their SADDR inputs driven to '1'. There-
fore, MT9M114 Master will respond to slave address ID0 (associated with SADDR = 0) and
all the other MT9M114 in the daisy-chain will respond simultaneously to slave address
ID1. Each MT9M114 has its CHAIN pin configured as an input. This situation is shown in
Figure 27. The host configures each MT9M114 in sequence, starting with the master and
ending with the farthest slave in the daisy-chain:
• MT9M114(1) Master: The host uses slave address ID0 (associated with SADDR = 0) and
therefore accesses registers on MT9M114(1) (the master). It writes to register
(R0x002E) to change the slave addresses associated with ID0 and ID1 on this device to
a single, new, unique value; call it ID-MT9M114(1). It then writes (using MT9M114(1)
to register PAD_CONTROL (R0x0032) to configure CHAIN as an output. Finally, it
writes (using MT9M114(1)) to the CHAIN_CONTROL register to set chain_enable =1,
MT9M114/D Rev. 11, 2/16 EN
43
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