Texas Instruments DRV2605LEVM-MD, User Manual

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TCA9548A - I
2
C Switch
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Table 5 lists the sequence for how to command the TCA9548A I
2
C switch. Any combination of channels
can be selected. When the slave address of the TCA9548A device is set, a single byte is required to
initialize channel selection. No register address is needed to send the channel selection value, but if a
register input must be available for the I
2
C write function, use the data value as the register value because
the device will take the last byte sent to it.
6.1 I
2
C Register Value Examples
The examples listed in Table 6 and Table 7 show exact I
2
C transactions with slave addresses, registers,
and values to enable one DRV2605L device and to enable three or more DRV2605L devices.
Table 6. TCA9548A I
2
C Transaction for Enabling Driver 1
I
2
C Action Slave Address (7-bit) Register Value Description
Configures I
2
C switch to connect
1 Write 0x70 N/A 0x01
channel 1 I
2
C lines
Table 7. TCA9548A I
2
C Transaction for Enabling Driver 1, 4, 5, and 8
I
2
C Action Slave Address (7-bit) Register Value Description
Configures I
2
C switch to contact
1 Write 0x70 N/A 0x99 channel 1, 4, 5, and (corresponds to
drivers 1, 4, 5, 8).
6.2 Operation Analysis
The TCA9548A operation can be verified with a logic analyzer hooked up to the master I
2
C bus input into
the device and to the channel outputs. Figure 10 shows the data and clock lines of the I
2
C commands to
the switch and to the GPIO expander to show proper operation of the devices together.
Figure 10. TCA9548A Logic Analyzer Operation
The TCA9554 device is first configured for output ports for drivers 6 and 7 with a value of 1 at the output.
The TCA9548A device is switched to driver 7 (channel 8) and sent a read command to the DRV2605L
device to verify communication with the haptic driver. The switch is then configured to select driver 6
(channel 7) and is then sent the same read command.
Figure 10 shows proper operation of the switch in
the case of isolating specific channels.
10 DRV2605L Multi-Driver ERM, LRA Haptic Driver Evaluation Kit User’s Guide SLOU400 – September 2014
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