Focussz Fosc21
The Focussz Fosc21 is a USB-based, 2-channel oscilloscope with an analog bandwidth of 3kHz and a sampling rate of 8kHz (1 channel) / 4kHz (2 channels). The manufacturer improperly calls this device an oscilloscope: It can only measure voltages from 0-5V, and thus cannot measure negative voltages.
See Focussz Fosc21/Info for more details (such as lsusb -vvv output) about the device.
Hardware
- Main chip: ST STM8S103 (marking: "STM8S103-K3T6C 990XB F6 MYS 136")
- USB interface: Prolific PL-2303HX (marking: "PL-2303HX LE10193A")
- Crystals: 12.000 and 22.1184
Photos
Device and probes
Package contents
Device, top
Device, bottom
Device, connectors
Device, back
PCB, top
PCB, bottom
ST STM8S103-K3T6C
Prolific PL2303HX
Protocol
The USB connector is nothing more than a PL2303 USB serial adapter. The port settings are the following:
115200,8n1
The host sends a 6-byte packet:
ff 05 61 7d 06 73
With the device responding
ff 0b 9b e6 80 1a 11 20 64 32 03 04
The first byte seems to be 0xff, indicating start of packet, with the second byte indicating the packet length (minus the first byte)
TODO.