ZKETECH EBD-USB

**ZKETECH EBD-USB+**
Status	supported
Source code	zketech-ebd-usb
Channels	1
Voltage/current (CH1)	35W / 0-4A / 0-21V
Connectivity	USB/serial
Features	DC constant current load
Website	zketech.com

The ZKETECH EBD-USB+ is a programmable DC electronic load (0~4A, 0~21V) with serial connectivity over USB.

The electronic load can only be used together with a computer, because it has no external controls.

Currently only the "plus" version is supported. Contact us for support if you own a "non-plus" version (25W / 13.5V).

See ZKETECH EBD-USB/Info for more details (such as lsusb -v output) about the device.

Hardware

Power MOSFET: Infineon IRLZ44N (datasheet)

Protocol

Messages are exchanged between host and devices:

they start with 0xfa
they end with 0xf8
these two bytes values can't be used in the rest of the message (the maximum value is 240)
the second byte encodes the message type
all two-byte values are in base 240 (e.g. 01 0a = 250)
the second last byte is a XOR checksum of the message (excluding first and last byte).

The communication is prone to byte loss on both directions. Always verify the message length, checksum, and don't send the bytes too fast. Resend messages until the one expected next is received. Sometimes it doesn't send any messages anymore and doesn't react to sent messages. Then the only way to reset the device is to re-plug it.

Messages:

fa 05 00 00 00 00 00 00 05 f8
- direction: host to device
- description: start measurements
fa 06 00 00 00 00 00 00 06 f8
- direction: host to device
- description: stop measurements
fa 01 00 64 00 0a 00 00 6f f8
- direction: host to device
- description: start load
- content:
  - 00 64: current limit in 0.001 A
  - 00 0a: cutoff voltage in 0.01 V
  - 00 00: time limit in minutes
- note: the time limit is not enforced on the device. the device will report the minutes passed, and the host needs to stop the load
fa 02 00 00 00 00 00 00 02 f8
- direction: host to device
- description: toggle load on/off
fa 07 00 64 00 0a 00 00 69 f8
- direction: host to device
- description: update load
- content:
  - 00 64: current limit in 0.001 A
  - 00 0a: cutoff voltage in 0.01 V
  - 00 00: time limit in minutes
- note: the time limit is not enforced on the device. the device will report the minutes passed, and the host needs to stop the load
fa 04 00 14 c8 00 00 00 d8 f8
- direction: host to device
- description: calibrate
- content:
  - 00: 0x00 = low voltage, 0x01 = high voltage, 0x02 = low current, 0x03 = high current
  - 14 c8: voltage in 0.001 V or current in 0.0001 A
fa 00 00 00 14 c5 07 a9 07 ad 00 64 00 0a 00 00 1a a1 f8
- direction: device to host
- description: measurement, without load
- content:
  - 00 00: current in 0.0001 A
  - 14 c5: voltage in 0.001 V
  - 07 a9: voltage of D+ 0.001 V
  - 07 ad: voltage of D- 0.001 V
  - 00 64: current limit in 0.001 A
  - 00 0a: cutoff voltage in 0.01 V
  - 00 00: time limit in minutes
  - 1a: device (0x1a = EBD-USB+)
fa 0a 00 00 14 c5 07 a9 07 ad 00 64 00 0a 00 00 1a ab f8
- direction: device to host
- description: measurement, with load
- content: same as measurement, without load
fa 0a 00 0a 00 00 00 00 00 f8
- direction: device to host
- description: load timer
- content:
  - 00 0a: time minutes passed since load start
fa 64 00 00 00 00 01 3b 00 e7 01 50 09 6f 10 a0 1a 24 f8
- direction: device to host
- description: device measurement, without load
- content:
  - 00 00: current in 0.0001 A
  - 00 00: voltage in 0.001 V
  - 01 3b: voltage of D+ 0.001 V
  - 00 e7: voltage of D- 0.001 V
  - 01 50: version in 0.01
  - 09 6f: unknown (seems constant)
  - 10 a0: unknown (seems constant)
  - 1a: device (0x1a = EBD-USB+)
fa 6e 08 52 14 67 07 95 07 9c 01 50 09 6f 10 a0 1a d3 f8
- direction: device to host
- description: device measurement, with load
- content: same as device measurement, without load