Saleae Logic Analyzer - Manchester Decoding

[SirrCharles]

Hi There,

I'm trying to decode a simple Manchester signal using Saleae Logic Analyzer
I'm sending 8 bits 11111111 from my microcontroller.

My period is 10 mS and my signal is 1010101010101010.
So the frequency should 100 Hz

The total signal period for al 8 bits is 80 mS
Which should convert to 11111111 in Manchester code.

I've set the bitrate to 100 bits per second.

But the Saleae Logic Manchester decoder doesn't work.
What am i doing wrong?




Thanx in advance!

[RoGeorge]

Don't have Saleae, but I've tried with a sigrok based decoder, and it just works.

Install PulseView and try to use your logic analyzer from PulseView.  Trigger on first rising edge, then add an OOK decoder for Manchester decoding.

[SirrCharles]

I noticed that only with 00000000 or 11111111 Saleae doesn't detect the Manchester code.

If one bit is added to 00000000  for example 00100000 it will detect.
If one bit is added to 11111111 for example 11111101 it will detect.

Parity Bit
I've added a 9th parity bit at the end of the 8-bit sequence.

When even      add 1
When sum is 0 add 1
When uneven   add 0

With a parity bit it seems to work for some strange reason.
11111111 & 00000000  are valid values for a byte and should be detected by the analyzer.
 

[SirrCharles]

Don't have Saleae, but I've tried with a sigrok based decoder, and it just works.

Install PulseView and try to use your logic analyzer from PulseView.  Trigger on first raising edge, then add an OOK decoder for Mancester decoding.

Thanks for going trough the effort of simulating this.

I downloaded PulseView but my Saleae Logic 8 is not supported only Saleae Logic 16 as it looks from the dropdown menu.

[horo]

It is supported as well as all the cheap 8 and 16 channel clones!

1. Chose the driver fx2lafw (generic driver for FX2 based LAs) (fx2lafw)
2. Chose USB
3. Scan for devices
4. Select Saleae Logic with 8 channels

USB IDs:
Saleae: idVendor=0925, idProduct=3881
Clones: idVendor=04b4, idProduct=8613