Hantek DDS-3X25

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

Hardware

TODO.

Photos

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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

Byte 1: bits 0-7 - point count LSB Byte 2: bits 0-3 - point count MSB, bit 7 - 0=transfer end, 1=transfer start Point count is 12 bits.

• 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