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MHINSTEK UDB1305S persp.jpg
Status planned
Frequency (user) 0.01Hz-2MHz/5MHz/8MHz
Waveforms sine/square/triangle/sawtooth, TTL rect
Amplitude 10 V (open)/5 V (50 Ohm) (adjustable)
Connectivity Serial TTL (3.3V)

The UDB1302S/UDB1305S/UDB1308S is a Dual-Channel standalone function generator. It can be controlled with the push-buttons and the rotary encoder, or via a bidirectional serial interface.

Amplitude and offset voltage can only be controlled using potentiometers.

This device can be bought on ebay or aliexpress from various sellers for 40€/50€/60€.


  • CPLD: Altera MAXII
  • Clock: 34.56MHz
  • STM8S105K4 8-bit MCU with 16 Kbytes Flash, 16 MHz CPU, integrated EEPROM STM8S10K54 procuct page
  • 74AHC14 Hex inverting Schmitt trigger (TTL output buffer, Freq/counter input buffer)



All models communicate via an serial connection, at either 19200 or 57600 bps, 8 bits, no parity, and 1 stop bit (57600/8n1 or 19200/8n1). Connecting to the devices can be done with any USB-serial converter. Signalling level is 3.3V

UDB1505S uses 57600 bps.


The generator will respond to commands, which consist of a short ASCII string followed by CR (additional LFs are ignored). The meter will either send no response at all or some ASCII text followed by CR+LF.

There a three classes of commands:

  1. Identication
  2. Set request
  3. Get request

Most set requests have a corresponding get request.

Identification command

→ a
← UDB1305S

Set/get requests

Select channel A/B

→ bh1
← ok

→ bh2
← ok

Query (ch) always reports channel 0 (i.e. neither 1 or 2)

Set/get frequency

5 MHz
→ bf500000000
← ok

→ cf
← cf500000000

2 kHz
→ bf000200000
← ok

→ cf
← cf000200000

1 Hz
→ bf      100
← ok

→ cf
← cf000000100