Difference between revisions of "Victor 70C"

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See [[Victor 70C/Info]] for more details (such as '''lsusb -vvv''' output) about the device.
See [[Victor 70C/Info]] for more details (such as '''lsusb -vvv''' output) about the device.
The USB protocol this device uses to communicate with the PC is documented on the [[Victor protocol]] page.


== Hardware ==
== Hardware ==
Line 12: Line 14:
* [http://datasheet.octopart.com/TLC27L2CP-Texas-Instruments-datasheet-151061.pdf Texas Instruments 27L2C] precision dual op-amp
* [http://datasheet.octopart.com/TLC27L2CP-Texas-Instruments-datasheet-151061.pdf Texas Instruments 27L2C] precision dual op-amp
* Unknown USB interface chip (HID)
* Unknown USB interface chip (HID)
Note: the USB/HID chip is ''in the multimeter'' (not in the USB cable/connector) for this device. The device is connected to the PC using a standard USB cable (without any internal logic/chip).


== Photos ==
== Photos ==
Line 26: Line 30:
</gallery>
</gallery>


== Protocol ==
The device registers on the USB host as a HID-class device ("Boot Interface" subclass), see [[Victor_70C/Info#lsusb|lsusb]]. Note: The USB/HID chip is ''in the multimeter'' (not in the USB cable/connector) for this device. The device is connected to the PC using a standard USB cable (without any internal logic/chip).
The protocol payload is 14 bytes of data which can be read from endpoint 1, at no more than 1 Hz.
The 14-byte chunk is somewhat obfuscated. To deobfuscate, subtract the ASCII value of the following string from each of the 14 bytes in turn: '''<code>jodenxunickxia</code>'''. Then reshuffle the bytes into different positions, according to the following table:
{| border="0" width="50%" style="font-size: smaller" class="alternategrey sigroktable"
|-
| Original position
| &nbsp;0
| &nbsp;1
| &nbsp;2
| &nbsp;3
| &nbsp;4
| &nbsp;5
| &nbsp;6
| &nbsp;7
| &nbsp;8
| &nbsp;9
| 10
| 11
| 12
| 13
|-
| Final position
| &nbsp;6
| 13
| &nbsp;5
| 11
| &nbsp;2
| &nbsp;7
| &nbsp;9
| &nbsp;8
| &nbsp;3
| 10
| 12
| &nbsp;0
| &nbsp;4
| &nbsp;1
|}
The deobfuscated payload is then structured as follows:
{| border="0" width="95%" style="font-size: smaller" class="alternategrey sigroktable"
|-
! style="width: 3em;" | Byte
! style="width: 3em;" | Bit
! Value
|-
| 0
|
| ''Unused (always contains 0x50).''
|-
| 1
|
| ''Unused (always contains 0xb0).''
|-
| 2
|
| ''Flags.''
|-
|
| 0
| Minus.
|-
|
| 1-7
| Unused.
|-
| 3
|
| ''Major measurement modes.''
|-
|
| 0
| Voltage measurement mode, combined with '''AC''' or '''DC''' flags in byte 6. In combination with the '''Diode''' flag in byte 4, signifies diode testing mode.
|-
|
| 1
| Current measurement mode, combined with '''AC''' or '''DC''' flags in byte 6.
|-
|
| 2
| Resistance measurement mode. In combination with the '''Continuity''' flag in byte 4, signifies continuity testing mode.
|-
|
| 3
| Unused.
|-
|
| 4
| Frequency measurement mode.
|-
|
| 5
| Capacitance measurement mode.
|-
|
| 6
| Temperature measurement mode, in degrees Celcius.
|-
|
| 7
| Temperature measurement mode, in Fahrenheit.
|-
| 4
|
| ''Value factors and extra measurement modes.''
|-
|
| 0
| µ (Micro).
|-
|
| 1
| m (Milli).
|-
|
| 2
| k (Kilo).
|-
|
| 3
| M (Mega).
|-
|
| 4
| Continuity (in combination with resistance mode in byte 3).
|-
|
| 5
| Diode (in combination with voltage mode in byte 3).
|-
|
| 6
| Duty cycle measurement mode.
|-
|
| 7
| Unused.
|-
| 5
|
| ''Extra flags and value factors.''
|-
|
| 0
| Unused.
|-
|
| 1
| Unused.
|-
|
| 2
| Max measurement mode.
|-
|
| 3
| Min measurement mode.
|-
|
| 4
| Unused.
|-
|
| 5
| Unused.
|-
|
| 6
| n (Nano).
|-
|
| 7
| Unused.
|-
| 6
|
| ''Flags.''
|-
|
| 0
| Unused.
|-
|
| 1
| Unused.
|-
|
| 2
| Auto-ranging mode.
|-
|
| 3
| DC measurement.
|-
|
| 4
| AC measurement.
|-
|
| 5
| Relative measurement.
|-
|
| 6
| Hold mode.
|-
|
| 7
| Unused.
|-
| 7
|
| ''Decimal point position.''
|-
|
| 0
| No decimal point.
|-
|
| 1
| Rightmost (1 digit after point).
|-
|
| 2
| Middle (2 digits after point).
|-
|
| 3
| Leftmost (3 digits after point).
|-
|
| 4
| Unused.
|-
|
| 5
| Unused.
|-
|
| 6
| Unused.
|-
|
| 7
| Unused.
|-
| 8
|
| ''Unused (always contains 0x04).''
|-
| 9
|
| ''Least significant digit on display.''
|-
| 10
|
| ''Second digit from right.''
|-
| 11
|
| ''Second digit from left.''
|-
| 12
|
| ''Most significant digit.''
|-
| 13
|
| ''Unused (always contains 0xd4).''
|}


== Resources ==
== Resources ==

Revision as of 23:49, 28 September 2012

Victor 70C

The Victor 70C is a 4000 counts, CAT II handheld digital multimeter with USB connectivity. It is also sold as the EZA EZ-735.

See Victor 70C/Info for more details (such as lsusb -vvv output) about the device.

The USB protocol this device uses to communicate with the PC is documented on the Victor protocol page.

Hardware

Note: the USB/HID chip is in the multimeter (not in the USB cable/connector) for this device. The device is connected to the PC using a standard USB cable (without any internal logic/chip).

Photos

  • Device, front

  • PCB, front

  • PCB, bottom

  • DMM/LCD chip

  • NXP HEF4066BT

  • Microchip TC7660E

  • TI 27L2C

  • LCD


Resources

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