Hi there,
I bought a small "TFT USB Digital Tester" with Bluetooth. Model J7-c.
It shows f.g. voltage, current, resistance and calculates capacity.
There are apps for iOS in the store and several versions for Android somewhere on a cloud storage...
And I didn´t want to install one of these!
This device has Bluetooth LE and classic Bluetooth SPP at the same time. Whatever you will use, data will be transferred constantly.
The data is in Hexadecimal and looks like that: 00 CD FF 55 01 03 00 01 FB 00 00 07 00 00 13 00 00 00 09 00 8C 00 EC 00 1F 00 00 0F 15 3C 0D AC 01 2C 03 20
A dataset consists of 36 bytes. There is a little delay between those datasets.
On my testing, the last 7 bytes remain the same:
Byte Pos.
Hex
Char
Description
30
0x3C
<
Smaller than
31
0x0D
CR
Carriage Return
32
0xAC
¬
?
33
0x01
SOH
Start of Header
34
0x2C
,
Comma
35
0x03
ETX
End of transmission
36
0x20
Space
At the beginning there are also several bytes not changing (except second):
Byte Pos.
Hex
Char
Description
1
0x00
Zero
3
0xFF
Int 255 (mostly "null")
4
0x55
U
5
0x01
SOH
Start of Header
6
0x03
ETX
End of transmission
SOH and ETX does not make any sense to me there. Maybe none-static values, which just does not change on my test.
Which seem to be the data bytes:
Byte Pos.
Hex
Value
10
00 00 07
0.07A
13
00 00 13
0000.13Wh
16
00 00 00 09
?
20
00 8C
?
22
00 EC
?
24
00 1F
31° C
The display changes constantly, so does the data. So it´s hard to capture the matching Hex values to the display. But this was what I saw at the time:
No. 01
5.09V
0.07A
00020mAh
0.36W
075.7 Ohm
0000:20:01 Time (20min 1 sec)
CPU 31°C
There are also the USB Datalines, which went crazy a lot, so I use min and max values.
V+: 5.09V (similar to main Voltage)
V-: 0V
D+: 0.72V - 2.18V
D-: 0.10V - 1.53V
That´s it for now. I´ll try again tomorrow with more data and screenshots.
Maybe you also got one of these or are just curious to findout more about the protocol. Feel free to participate
Tested my Notebook today.
The direction was the other way around, so was the orientation (by Setup). But nothing changed on the first 6 bytes. Also the 30th was as constant as it was before.
On the display Fast Charge was stated and the 19,8V. With my smartphone it was QC2 (Quick Charge)
So I guess I´ll end up here. Maybe I´ll write an Arduino Sketch to transfer the data readable to my PC via serial. Or directly build a .Net application, which gets it´s data directly via bluetooth.
