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Operation
4.2.3.2 Collect Data Through the USB BULK Channel
The Collect Data function can also be started and stopped through the serial COM port, however the results will
be sent over the USB BULK Channel. To do this, use the following format:
•
Start collecting data format: collect timerPeriod collectFlags channelAddressIDs numDevices
– Where each parameter is the decimal representation of the value in the following format:
•
timerPeriod: The delay used in the internal timer to allow data collection sample sets (in milliseconds,
unsigned 32-bit value).
•
collectFlags: a byte of data that has a 1 to collect and a 0 to not collect each register value type,
according to the following definitions (note to only use energy and charge flags when the device
supports that, otherwise set to 0):
– VSHUNT = 0b1000000
– VBUS = 0b0100000
– CURRENT = 0b0001000
– POWER = 0b0000100
•
channelAddressIDs
– This is the 4 LSBs of each address chained together, starting with the LSBs.
•
For example If EVM 1 is on channel 0x41 and EVM 2 is on 0x43, the value here would be
0b00110001
•
NumDevices is the number of EVMs chained together (1-4).
– For example, to start data collection for VSHUNT, VBUS, and CURRENT and POWER every 10 ms, for
four INA236s with EVM 1 SW0 = GND, EVM 2 SW0 = VS, EVM 3 SW0 = SDA and EVM 4 SW0 = SCL,
you would send: collect 10 108 12816 4
•
For this example, the EVM would return the acknowledgment and status in JSON format:
{"acknowledge":"collect 10 108 12816 4"}
{"evm_state":"collecting"}
•
Note, for the rreg and wreg functions above, the EVM will return "collecting" instead of "idle" if
collecting.
– The USB BULK channel receives data in the format: frameID deviceNumID address registerSize data
•
Where each parameter is the decimal representation of the value in the following format:
– frameID (1 byte): Always reads 0. Used to ensure data is aligned.
– deviceNumID (1 byte): An ID number corresponding to the EVM number.
•
From the above example, this will be 1 if reading from EVM 1, 2 from EVM 2, 3 from EVM 3, and
4 from EVM 4.
– address (1 byte): The register address that was read from the device.
– registerSize (1 byte): The number of bytes that the following data will have.
– data (1 byte at a time): The register data value, given in bytes with the most significant byte first.
•
Stop collecting data format: stop
– The EVM would return the acknowledgment and status in JSON format:
{"acknowledge":"stop"}
{"evm_state":"idle"}
14
INA234EVM and INA236EVM
Copyright © 2021 Texas Instruments Incorporated
www.ti.com
SBOU264 – MAY 2021
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