GS6152 Datasheet, PDF (38/80 Pages) Semtech Corporation – Multi-Rate 6G UHD-SDI

SCLK
CS
t₅
SDIN
COMMAND
High-z
SDOUT
COMMAND
X
DATA 1
DATA 2
Figure 4-20: GSPI Read Timing – Auto-Increment Read with Bus-through Operation
4.11.9 Setting a Device Unit Address
Multiple (up to 32) GS6152 devices can be connected to a common Chip Select (CS) in
Loop-Through or Bus-Through operation.
To ensure that each device selected by a common CS can be separately addressed, a
unique Unit Address must be programmed by the host processor at start-up as part of
system initialization or following a device reset.
Note: By default at power up or after a device reset, the DEVICE_UNIT_ADDRESS of each
device is set to 0h and the SDIN->SDOUT non-clocked loop-through for each device is
enabled.
These are the steps required to set the DEVICE_UNIT_ADDRESS of devices in a chain to
values other than 0:
1. Write to Unit Address 0 selecting HOST_CONFIG (ADDRESS = 0), with the
GSPI_LINK_DISABLE bit set to 1 and the DEVICE_UNIT_ADDRESS field set to 0. This
disables the direct SDIN->SDOUT non-clocked path for all devices on chip select.
2. Write to Unit Address 0 selecting HOST_CONFIG (ADDRESS = 0), with the
GSPI_LINK_DISABLE bit set to 0 and the DEVICE_UNIT_ADDRESS field set to a
unique Unit Address. This configures DEVICE_UNIT_ADDRESS for the first device in
the chain. Each subsequent such write to Unit Address 0 will configure the next
device in the chain. If there are 32 devices in a chain, the last (32nd) device in the
chain must use DEVICE_UNIT_ADDRESS value 0.
3. Repeat step 2 using new, unique values for the DEVICE_UNIT_ADDRESS field in
HOST_CONFIG until all devices in the chain have been configured with their own
unique Unit Address value.
Note: t_{cmd_GSPI_conf} delay must be observed after every write that modifies
HOST_CONFIG.
All connected devices receive this command (by default the Unit Address of all devices
is 0), and the Loop-Through operation will be re-established for all connected devices.
Once configured, each device will only respond to Command Words with a
UNIT ADDRESS field matching the DEVICE_UNIT_ADDRESS in HOST_CONFIG
Note: Although the Loop-Through and Bus-Through configurations are compatible
with previous generation GSPI enabled devices (backward compatibility), only devices
supporting Unit Addressing can share a chip select. All devices on any single chip select
must be connected in a contiguous chain with only the last device's SDOUT connected
to the application host processor. Multiple chains configured in Bus-Through mode can
have their final SDOUT outputs connected to a single application host processor input.
GS6152
Final Data Sheet
PDS-060984
Rev.2
July 2015
www.semtech.com
38 of 80
Semtech
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