Difference between revisions of "UNI-T UT372"
Uwe Hermann (talk | contribs) (UT372 is supported.) |
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{{Infobox multimeter | {{Infobox multimeter | ||
| image = [[File: | | image = [[File:Uni-t ut372 mugshot.png|180px]] | ||
| name = UNI-T UT372 | | name = UNI-T UT372 | ||
| status = supported | | status = supported | ||
| Line 9: | Line 9: | ||
| measurements = rpm, counts | | measurements = rpm, counts | ||
| features = | | features = | ||
| website = [http://uni-trend.com/ | | website = [http://uni-trend.com/productsdetail.aspx?ProductsID=789&ProductsCateId=804&CateId=804 uni-trend.com] | ||
}} | }} | ||
Latest revision as of 19:59, 20 April 2017
 | |
| 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
- Silicon Labs C8051F313 MCU
- Holtek HT1621B LCD controller
- 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.
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 | - | - |