InsideGadgets Logic Observer

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insideGadgets Logic Observer
Status planned
Channels 8
Samplerate 50MHz
Samplerate (state)
Triggers high, low
Min/max voltage 2V — 5.5V
Threshold voltage ?
Memory 131ksamples/ch
Compression none

The insideGadgets Logic Observer is an 8-channel logic analyzer with up to 50MHz sampling rate. It is a mostly open project with all source code (CPLD, MCU) available, as well as a schematic of the PCB.

See insideGadgets Logic Observer/Info for more details (such as lsusb -v output) about the device.



The device is controlled entirely via USB control messages. The command is encoded in the request value of the control message; value and index are unused.

The following requests are defined:


This tells the device to transfer the samples captured in memory to the host. This is called multiple times; the buffer memory is transferred 254 bytes at a time, with the address increasing automatically. The address is reset when a capture is started or settings are updated.


Send new settings to the device. The settings consist of the following eight bytes sent along with the control request:

Byte Description
0 Bitmask of the channels to trigger on. All channels marked according to the trigger level must match before a trigger is considered to have fired.
1 Level to trigger on (0 or 1).
2 Delay after trigger, in milliseconds.
3 Trigger count: number of times the trigger must fire before the capture starts.
4 Sample rate, as follows:
Value Sample rate
80 50 MS/S
0 10 MS/S
1 5 MS/S
3 2.5 MS/S
9 1 MS/S
19 500 KS/S
39 250 KS/S
99 100 KS/S
5 Number of samples to capture
6 Start capture flag: a capture is started if this is not 0.
7 Always 0.


Returns a 2-byte status field. The first byte indicates whether capturing has finished (1) or not (0). The second byte is always 0.


This cancels a capture in progress.