Hantek DDS-3X25

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Hantek DDS-3X25
Hantek DDS-3X25 top.jpg
Status planned
Frequency (user) 25MHz
Waveforms user only
Waveform memory 4000 points
Amplitude 0 - 3.5V
Connectivity USB
Website hantek.com

The Hantek DDS-3X25 is a 25MHz PC-based function generator. It has no external controls, requiring a USB connection to a computer.

See Hantek DDS-3X25/Info for more details (such as lsusb -vvv output) about the device.

Hardware

  • FPGA: Xylinx Spartan? 144 pins (20 MHz clock)
  • Microcontroller: STM32F103C6(T6A) Mainstream Performance line, ARM Cortex-M3 MCU with 32 Kbytes Flash, 72 MHz CPU, motor control, USB and CAN (8 MHz? clock)
  • Output amplifier: LMH6702 1.7 GHz, Ultra Low Distortion, Wideband Op Amp.
  • Sync signal output is connected without any buffer or amplifier.
  • COUNT IN is connected through TL3016 ULTRA-FAST LOW-POWER PRECISION COMPARATOR.
  • Isolated unregulated DC-DC converter MORNSUN A0505S-2W, ±5V, ±200mA

Photos

Protocol

Waveform samples

When sending a waveform to the device, a series of samples denote voltage. These are 12-bit values packed in padded 16-bit integers, sent in network order (most significant part first):

  • bits 0-9 are the value, with encoding as shown below
  • bit 10
  • bit 11 is the sign: 1 for positive, 0 for negative
  • bit 12 controls the "sync out" port: 1 is on, 0 is off
  • bits 13 is always 1, bits 14-15 are always 0

The value is encoded as 2048 - (voltage * 585). Negative values have all sign and value bits complemented (reversed).

0xA0: configure

Configures the device. The payload is 6 bytes:

Byte Bit Description
1 Mode
7
6
5 1 = Reset external trigger (send only once)
4 1 = External trigger mode enabled
3 External trigger: 0 = falling, 1 = rising
2 0 = continuous, 1 = single wave
1 Counter reset: 0 = leave, 1 = reset
0 Measurement: 0 = frequency, 1 = counter
2
7
6
5
4
3
2
1
0 Output: 0 = pattern generator, 1 = programmable output
3 Digital I/O pins, bits 0-7
4 Bits 0-3 = digital I/O pins bits 8-11, bits 4-7 unused
5 Clock divider, based on 48KHz clock
6

THe response is 10 bytes:

  • the first 2 bytes are always 0
  • in frequency measurement mode:
    • four bytes for the current frequency measurement, in network order. Multiply by 2 to get the actual frequency readout.
    • four bytes for a "tick counter" in network order. This has the number of ticks per second, and is used to derive the frequency. Assuming a 100Mhz clock, this counter differs up to 4.17% at 8Mhz from the derived frequency -- investigate.
  • in counter mode:
    • four bytes for the current counter, in network order.
    • four bytes denoting the smoothed out frequency, identical to the first four bytes in frequency measurement mode.

0xA1: point transfer indicator

The payload is 2 bytes:

Byte Bit Description
1 0-7 Bits 0-7 of the waveform point count
2 0-3 Bits 8-11 of the waveform point count
4-6 Unused
7 0=transfer end, 1=transfer start

There is a 1-byte response: 0xcc

0xA2: unknown

  • 6-byte payload: 0000 0000 3000
  • 1-byte response: 0xcd

When setting "close output power on", i.e. save configuration to memory:

  • no payload
  • 1-byte response: 0xcd

0xA3: unknown

  • no payload
  • 1-byte response: 0x02

Resources