Difference between revisions of "UNI-T UT372"

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(→‎Protocol: Extra time digit)
m (Fixed UT-372 URL)
 
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{{Infobox multimeter
{{Infobox multimeter
| image          = [[File:UT372_front.jpg|60px]]
| image          = [[File:Uni-t ut372 mugshot.png|180px]]
| name            = UNI-T UT372
| name            = UNI-T UT372
| status          = in progress
| status          = supported
| source_code_dir =  
| source_code_dir = uni-t-dmm
| counts          = 99999
| categories      =  
| connectivity    = USB
| connectivity    = USB
| website        = [http://www.uni-trend.com/UT372.html uni-trend.com]
| measurements    = rpm, counts
| features        =
| website        = [http://uni-trend.com/productsdetail.aspx?ProductsID=789&ProductsCateId=804&CateId=804 uni-trend.com]
}}
}}


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* [http://www.silabs.com/Support%20Documents/TechnicalDocs/C8051F313-short.pdf Silicon Labs C8051F313] MCU
* [http://www.silabs.com/Support%20Documents/TechnicalDocs/C8051F313-short.pdf Silicon Labs C8051F313] MCU
* [http://www.goldenviewdisplay.com/pdf/LCD_controllers/ht1621.pdf Holtek HT1621B] LCD controller
* [http://www.goldenviewdisplay.com/pdf/LCD_controllers/ht1621.pdf Holtek HT1621B] LCD controller
* [[WCH_CH9325 | WCH CH9325]] USB UART interface
* [[WCH CH9325]] USB UART interface


The unit includes a built in laser pointer for aiming at a reflective target, and a tripod fitting to allow stable mounting.
The unit includes a built in laser pointer for aiming at a reflective target, and a tripod fitting to allow stable mounting.
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<gallery>
<gallery>
File:UT372_front.jpg
File:UT372_front.jpg|<small>Device, front</small>
File:UT372_back.jpg
File:UT372_back.jpg|<small>Device, back</small>
File:UT372_pcb.jpg
File:UT372_pcb.jpg|<small>PCB, top</small>
</gallery>
</gallery>


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The packet is processed to turn it into a valid hex string - any character with an ASCII value above 0x39 is shifted up by 7 characters, putting it into the range 'A' to 'F'.
The packet is processed to turn it into a valid hex string - any character with an ASCII value above 0x39 is shifted up by 7 characters, putting it into the range 'A' to 'F'.


The first character seems to be ignored. The next 5 pairs of characters represent the RPM (least significant digit first). The next 5 pairs of characters represent the time (least significant digit first). The remaining characters are unknown at this point.
The first character seems to be ignored. The next 5 pairs of characters represent the RPM (least significant digit first). The next 5 pairs of characters represent the time (least significant digit first). The final 2 pairs of characters represent the remaining segments of the display.


Each pair of characters, when interpreted as a single hex byte, is a bitfield representing the on/off state of segments on the display. A look-up table is provided below. Setting the most significant bit indicates that a decimal point is placed after that digit.
Each pair of characters, when interpreted as a single hex byte, is a bitfield representing the on/off state of segments on the display. A look-up table is provided below. Setting the most significant bit indicates that a decimal point is placed after that digit.


{| border="0" class="alternategrey sigroktable sortable"
=== LCD character lookup ===
 
{| border="0" style="font-size: smaller" class="alternategrey sigroktable sortable"
|-
|-
! style="width: 5em; text-align: left;" | String
! style="width:5em; text-align: left;" | String
! style="text-align: left;" | Hex Byte
! style="text-align: left;" | Hex byte
! style="text-align: left;" | Character
! style="text-align: left;" | Character
|-
|-
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| 0x0B
| 0x0B
| L
| L
|-
|}
=== Other display segments ===
{| border="0" style="font-size: smaller" class="alternategrey sigroktable sortable"
|-
! style="width:5em; text-align: left;" | Bit&nbsp;(LSB&nbsp;#0)
! style="text-align: left;" | First byte
! style="text-align: left;" | Second byte
|-
| 0
| -
| RPM
|-
| 1
| BATT
| COUNT
|-
| 2
| HOLD
| -
|-
| 3
| -
| -
|-
| 4
| LED
| MAX
|-
| 5
| -
| MIN
|-
| 6
| -
| AVE
|-
| 7
| -
| -
|-
|-
|}
|}
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[[Category:Device]]
[[Category:Device]]
[[Category:Tachometer]]
[[Category:Tachometer]]
[[Category:In progress]]
[[Category:Supported]]

Latest revision as of 19:59, 20 April 2017

UNI-T UT372
Uni-t ut372 mugshot.png
Status supported
Source code uni-t-dmm
Counts 99999
Connectivity USB
Measurements rpm, counts
Website uni-trend.com

The UNI-T UT372 is a digital tachometer with USB connectivity.

Hardware

The unit includes a built in laser pointer for aiming at a reflective target, and a tripod fitting to allow stable mounting.

Photos

  • Device, front

  • Device, back

  • PCB, top

Protocol

The MCU transmits serial data to the CH9325 at 2400 baud. A packet is 27 bytes of ASCII data ending in CR, LF.

The packet is processed to turn it into a valid hex string - any character with an ASCII value above 0x39 is shifted up by 7 characters, putting it into the range 'A' to 'F'.

The first character seems to be ignored. The next 5 pairs of characters represent the RPM (least significant digit first). The next 5 pairs of characters represent the time (least significant digit first). The final 2 pairs of characters represent the remaining segments of the display.

Each pair of characters, when interpreted as a single hex byte, is a bitfield representing the on/off state of segments on the display. A look-up table is provided below. Setting the most significant bit indicates that a decimal point is placed after that digit.

LCD character lookup

String Hex byte Character
"7;" 0x7B 0
"60" 0x60 1
"5>" 0x5E 2
"7<" 0x7C 3
"65" 0x65 4
"3=" 0x3D 5
"3?" 0x3F 6
"70" 0x70 7
"7?" 0x7F 8
"7=" 0x7D 9
"0;" 0x0B L

Other display segments

Bit (LSB #0) First byte Second byte
0 - RPM
1 BATT COUNT
2 HOLD -
3 - -
4 LED MAX
5 - MIN
6 - AVE
7 - -

Resources

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