Library work well with TF mini but error for TF mini Plus

[VaAndCob]

my controller is Arduino Pro mini
the library works well with TFmini model

36 cm sigstr: 119
36 cm sigstr: 120
36 cm sigstr: 120
36 cm sigstr: 119
36 cm sigstr: 120

but when I connect to TFmini plus (a model come with IP56 enclosure)
the error occurred repeatly.

Last error:
ERROR_SERIAL_BADCHECKSUM
65535 cm sigstr: 65535

Remark: TFmini plus work well with Benewake TF test software

[PeterAJansen]

That's interesting... can you point me to a datasheet for the TF mini plus?

[VaAndCob]

http://en.benewake.com/res/wuliu/docs/15487893679657874SJ-GU-TFmini%20Plus-01-A02-Datasheet_EN.pdf

here is the page for datasheet download

[PeterAJansen]

Here's a datasheet from Sparkfun: https://cdn.sparkfun.com/assets/2/b/0/3/8/TFmini_Plus-01-A02-Datasheet_EN.pdf

It looks like it's using very different commands than the TF mini. Feel free to update the driver (I would make a second class, TFMiniPlus). Or if someone sends one my way, I can try to do this update in between things.

[VaAndCob]

thank Peter,
I have tried to skip checksum byte comparison in the library.
the output with some error as shown below:

204 cm sigstr: 1354
204 cm sigstr: 1351
204 cm sigstr: 1350
52569 cm sigstr: 17408 (error)
22873 cm sigstr: 204 (error)
204 cm sigstr: 22855
205 cm sigstr: 1354
204 cm sigstr: 1347
205 cm sigstr: 1356
52313 cm sigstr: 17152 (error)
22988 cm sigstr: 52057 (error)
204 cm sigstr: 1360
203 cm sigstr: 1356

[VaAndCob]

I notice that no matter the output distance is correct or not, checksum byte comparison will always be different.

checksum : checksumByte
0x69 : 0x59
44 cm sigstr: 5598
0x67 : 0x9C
22828 cm sigstr: 2390 (error)
0x62 : 0x6B
44 cm sigstr: 5591
0x68 : 0x0
44 cm sigstr: 23000
0xBC : 0x15
22828 cm sigstr: 11353 (error)
0x9B : 0xFB
2390 cm sigstr: 5593 (error)
0x68 : 0x59
44 cm sigstr: 5597
0x74 : 0x98
22873 cm sigstr: 44 (error)
// I don't know why...

[VaAndCob]

I found the cause that make checksum error.

// Store running checksum
if (i < TFMINI_FRAME_SIZE-2) {
checksum += frame[i];
}

code in file TFmini.cpp Line No. 140
I replace 2 with 1

// Store running checksum
if (i < TFMINI_FRAME_SIZE-1) {
checksum += frame[i];
}
it works normally now.

[sfambach]

Thanks thats worked for me to.

[DaveDixon]

In addition to Ratthanin's check sum change, I found I had to change takeMeasurement() also.

From

uint16_t dist = (frame[1] << 8) + frame[0];
uint16_t st = (frame[3] << 8) + frame[2];

To

uint16_t dist = (frame[1] << 7) + frame[0];
uint16_t st = (frame[3] << 7) + frame[2];