Difference between revisions of "SainSmart DDS120"

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(Move vendor protocol info, cleanup firmware info.)
(Moved firmware info, cleanups.)
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== Protocol ==
== Protocol ==


We use an open-source firmware that is part of [[fx2lafw|sigrok-firmware-fx2lafw]] for this device (i.e., not the vendor firmware/protocol), hence we do not need to know the vendor protocol.
We use an open-source firmware for this device (i.e., not the vendor firmware/protocol), hence we do not need to know the vendor protocol. There is some [[SainSmart_DDS120/Info#Vendor_firmware|historic vendor firmware/protocol info]] for those interested, though.
 
There is some [[SainSmart_DDS120/Info#Vendor_firmware|historic vendor firmware/protocol info]] for those interested, though.


== Firmware ==
== Firmware ==


The vendor firmware is contained on the I²C EEPROM. The FX2 boots directly into that firmware. However, we replace it (only in RAM, the EEPROM is never modified) with an open-source firmware that is part of [[fx2lafw|sigrok-firmware-fx2lafw]] when the device is attached to USB.
In order to use this device, the [[fx2lafw|sigrok-firmware-fx2lafw]] (>= 0.1.4) firmware is required.
 
The open source firmware is currently missing the following planned features:
 
* <1MHz, 2, 3, 5, 6, 7.5, 9.6, 10, 15, 24, 30 MHz sampling rate support
* Turn on/off the calibration pulse
* Change frequency of the calibration pulse (add 10kHz, 100kHz and 1MHz)
 
==== Gain stage ====
 
The gain stage is 2 stage approach. -6dB and -20dB on the first stage (attentuator). The second stage is then doing the gain by 3 different resistor values switched into the feedback loop. The following does not correlate with measure on real hardware, there is a 6th gain position that is working though. It is very similar to another gain and was most likely omitted because of that.
 
<small>
# Channel 0:
PC1=1; PC2=0; PC3= 0 -> Gain x0.1 = -20dB -> 0x02 (1V)
PC1=1; PC2=0; PC3= 1 -> Gain x0.2 = -14dB -> 0x0A (0.5V)
PC1=1; PC2=1; PC3= 0 -> Gain x0.4 =  -8dB -> 0x06 (0.250V)
PC1=0; PC2=0; PC3= 0 -> Gain x0.5 =  -6dB -> 0x00 (0.200V)
PC1=0; PC2=0; PC3= 1 -> Gain x1  =  0dB -> 0x08 (0.100V)
PC1=0; PC2=1; PC3= 0 -> Gain x2  =  +6dB -> 0x04 (0.050V)
# Channel 1:
PE1=1; PC4=0; PC5= 0 -> Gain x0.1 = -20dB -> 0x02 (1V)
PE1=1; PC4=0; PC5= 1 -> Gain x0.2 = -14dB -> 0x22 (0.5V)
PE1=1; PC4=1; PC5= 0 -> Gain x0.4 =  -8dB -> 0x12 (0.250V)
PE1=0; PC4=0; PC5= 0 -> Gain x0.5 =  -6dB -> 0x00 (0.200V)
PE1=0; PC4=0; PC5= 1 -> Gain x1  =  0dB -> 0x20 (0.100V)
PE1=0; PC4=1; PC5= 0 -> Gain x2  =  +6dB -> 0x10 (0.050V)
</small>
 
==== AC/DC coupling ====
 
The coupling is controlled via 2 PhotoMOS chips.
 
<small>
# Channel 0:
PE3=0 Disable AC-coupling capacitor (DC-coupling)
PE3=1 Enable AC-coupling capacitor
# Channel 1:
PE0=0 Disable AC-coupling capacitor (DC-coupling)
PE0=1 Enable AC-coupling capacitor
</small>
 
==== 1kHz calibration square wave ====
 
Pin PE2 controls the frequency of the calibration output on the PCB. It is driven by an ISR timer from the 8051 core of the FX2 chip.


== Resources ==
== Resources ==

Revision as of 20:28, 1 November 2016

SainSmart DDS120

The SainSmart DDS120 is a USB-based, 2-channel oscilloscope with an analog bandwidth of 20MS/s and 48MS/s sampling rate.

This device appears to be a rebadge of the Rocktech BM102 (or vice versa). The lsusb is exactly the same, the PCB is exactly the same (both have a "656517" and "102LJT1402" silkscreen), and the components used appear to be the same as well.

The device was apparently created by someone named "buudai" in 2012 (also reflected in the lsusb and in the former buudai.com website).

See SainSmart DDS120/Info for more details (such as lsusb -v output) about the device.

Hardware

Or in newer hardware:

Photos

Teardown 1:

  • Device, top

  • PCB, front

  • PCB, front

  • PCB, front

  • PCB, front

  • PCB, front

  • PCB, front

  • PCB, back

  • PCB, back

  • Box

  • Box

  • Box

Teardown 2 (purchased 03/2016):

  • Sticker

  • Package contents

  • Device, top

  • Device, bottom

  • USB

  • Connectors

  • PCB, top

  • PCB, bottom

  • MXTronix MXT2088

  • Cypress FX2

  • Microchip 24LC64I

  • TI CD4052BM

  • AMS1117-3.3

  • Unknown IC

Protocol

We use an open-source firmware for this device (i.e., not the vendor firmware/protocol), hence we do not need to know the vendor protocol. There is some historic vendor firmware/protocol info for those interested, though.

Firmware

In order to use this device, the sigrok-firmware-fx2lafw (>= 0.1.4) firmware is required.

Resources

Retrieved from "https://sigrok.org/w/index.php?title=SainSmart_DDS120&oldid=11979"