Difference between revisions of "SainSmart DDS120"

From sigrok
Jump to navigation Jump to search
(More info.)
(Move vendor protocol info, cleanup firmware info.)
Line 62: Line 62:
== Protocol ==
== Protocol ==


The vendor firmware uses the following 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.


{| border="0" style="font-size: smaller" class="alternategrey sortable sigroktable"
There is some [[SainSmart_DDS120/Info#Vendor_firmware|historic vendor firmware/protocol info]] for those interested, though.
|-
!Oscilloscope command
!bRequest value
!Notes
|-
|Set CH0 coupling ||0x24 ||Possible values: 0x00, 0x08 (AC-coupling, DC-coupling).
|-
|Set CH1 coupling ||0x25 ||Possible values: 0x20, 0x10 (AC-coupling, DC-coupling).
|-
|Set CH0 voltage range ||0x22 ||Possible values: 0x08, 0x04, 0x00, 0x06, 0x02 (50mV, 100mV, 200mV, 500mV, 1-5V).
|-
|Set CH1 voltage range ||0x23 ||Possible values: 0x20, 0x10, 0x00, 0x12, 0x02 (50mV, 100mV, 200mV, 500mV, 1-5V).
|-
|Set sampling rate ||0x94 ||Possible values: 0x11, 0x01, 0x10 (240kHz, 2.4MHz, 48MHz).
|-
|Trigger oscilloscope ||0x33 ||Possible values: 0x00 == start sampling.
|-
|}


== Firmware ==
== Firmware ==


=== Vendor 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.


The SainSmart vendor firmware is contained on the I²C EEPROM. The FX2 boots directly into that firmware.
The open source firmware is currently missing the following planned features:
 
=== Open-source firmware ===
 
There is an open-source firmware that can be used by sigrok. The open source firmware is missing the following planned features:


* <1MHz, 2, 3, 5, 6, 7.5, 9.6, 10, 15, 24, 30 MHz sampling rate support
* <1MHz, 2, 3, 5, 6, 7.5, 9.6, 10, 15, 24, 30 MHz sampling rate support
Line 102: Line 80:
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.
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:
  # Channel 0:
  PC1=1; PC2=0; PC3= 0 -> Gain x0.1 = -20dB -> 0x02 (1V)
  PC1=1; PC2=0; PC3= 0 -> Gain x0.1 = -20dB -> 0x02 (1V)
Line 117: Line 96:
  PE1=0; PC4=0; PC5= 1 -> Gain x1  =  0dB -> 0x20 (0.100V)
  PE1=0; PC4=0; PC5= 1 -> Gain x1  =  0dB -> 0x20 (0.100V)
  PE1=0; PC4=1; PC5= 0 -> Gain x2  =  +6dB -> 0x10 (0.050V)
  PE1=0; PC4=1; PC5= 0 -> Gain x2  =  +6dB -> 0x10 (0.050V)
</small>


==== AC/DC coupling ====
==== AC/DC coupling ====
Line 122: Line 102:
The coupling is controlled via 2 PhotoMOS chips.
The coupling is controlled via 2 PhotoMOS chips.


<small>
  # Channel 0:
  # Channel 0:
  PE3=0 Disable AC-coupling capacitor (DC-Coupling)
  PE3=0 Disable AC-coupling capacitor (DC-coupling)
  PE3=1 Enable AC-coupling capacitor
  PE3=1 Enable AC-coupling capacitor
   
   
  # Channel 1:
  # Channel 1:
  PE0=0 Disable AC-coupling capacitor (DC-Coupling)
  PE0=0 Disable AC-coupling capacitor (DC-coupling)
  PE0=1 Enable AC-coupling capacitor
  PE0=1 Enable AC-coupling capacitor
</small>


==== 1kHz calibration square wave ====
==== 1kHz calibration square wave ====

Revision as of 20:20, 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 that is part of sigrok-firmware-fx2lafw 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

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 sigrok-firmware-fx2lafw when the device is attached to USB.

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. 

# 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)

AC/DC coupling

The coupling is controlled via 2 PhotoMOS chips. 

# 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

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

Retrieved from "https://sigrok.org/w/index.php?title=SainSmart_DDS120&oldid=11977"