Difference between revisions of "UNI-T UT372"

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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.
Line 21: Line 25:


<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>


== Protocol ==
== 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 meaning of each part of the ASCII data is still to be decoded.
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 ===
 
{| border="0" style="font-size: smaller" class="alternategrey sigroktable sortable"
|-
! style="width:5em; text-align: left;" | String
! style="text-align: left;" | Hex byte
! style="text-align: left;" | 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 ===
 
{| 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
| -
| -
|-
|}


== Resources ==
== Resources ==
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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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