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xjtuecho / EBAZ4205

A 5$ Xilinx ZYNQ development board.
MIT License
627 stars 164 forks source link

Missing Components #13

Open firepower9966 opened 3 years ago

firepower9966 commented 3 years ago

I just received my EBAZ4205 from aliexpress, I noticed some components are missing compared to PCB in Photo Missing: (next to J5, J3 Fan Headers) U67, R2546, R2544, R2545 U68, R2548, R2549, R2547 U69, R2554, R2551 U70, R2557, R2555 Added: R2553, R2552, R2554, R2557 33 ohm 33 ohm resisters are bypassing the missing opto-isolators and resistors for PWM and SPEED for fan. Due to no Isolation be careful if applying more than the maximum allowed 1.2 to 3.3V of FPGA I/O set Voltage.

Missing: (next to U24 Lan) Y3 25MHz xtal C377, C380 22pF Added: R1485 33 ohms XOUT.0 used for clock for U24 LAN IC (I have added 25Mhz xtal and caps)

Missing: (next to U72) C2394 100nF C2398 3.9uF not really an issue as U72 IC and other components are missing and these are just extra bypass caps

Can Be Added: SWITCH S3 if you short out missing R2649 Zero Ohm Resistor. Or you can just link right leg of SW2 to right leg of SW3 if looking from front of PCB (leg closest to LAN socket)

X5 50MHz 3225 oscillator, you need to add 0 ohm resistor or link at R1372 and L29 on bottom of PCB (I have added 50MHz osc and links)

X3 RTC (Real Time Clock) possibly PCF8523 RTC Y2 32.6678 kHz 3x8

tpecar commented 3 years ago

There are at least two known hardware revisions of the board:

  1. version, pictured in the repo README, which has the phy crystal + optocouplers
  2. version (what you have), where these components (+various resistors and caps) are missing

They presumably use the same PCB. It has been speculated that they have different software / bitstream configurations and that in the 2nd version the FPGA generates the clock for the phy.

However, I haven't looked into this myself, other members may have more information on this.

Kudos for identifying the missing components and measuring their values - I suggest that you add them to hardware build states wiki page.

tpecar commented 3 years ago

Also, it's probably a good idea that people start nagging their sellers to partially refund them for falsely advertising their product and to force them to update the product image.

Most, if not all, sellers use the 1. version for the product image (which was probably made early in the devices product cycle) but sell you the 2nd. There have been numerous reports about this already.

firepower9966 commented 3 years ago

my seller sold both types, i selected the cheaper version which had no sdcard and jumpers, but they were supplied to be soldered by user. did not realized other components were missing though, pictures of both boards were shown. I updated wiki as suggested.

nic3-14159 commented 3 years ago

Mine was missing the opto-isolators and 25MHz crystal as well, where the opto-isolators were bypassed by those extra 33 ohm resistors. I took a look at the schematic and my board and found that the 10k ohm resistors R1344 and R1361 are pull-ups to 3.3V on pin 3 (labeled as SPEED on the board) of both J3 and J5. So using logic levels of less than 3.3V on those pins should probably be avoided if using a board with the missing components. Alternatively, just remove those resistors.

Looking at the schematic again, it seems like if the opto-isolators are present, R2350 (the board seems to say R2550, but the schematic says R2350) and R2556 pull up pin 4 on J3/J5 to VCC8, which is whatever voltage is on J4 or pin 2 on J3/J5. Those resistors are missing on the 2nd version of the board. With the opto-isolator, pin 4 (labled as PWM on the board) can only be used as an output, and the pull-up resistors means that the logical high voltage will be whatever VCC8 is. So if you have added the D24 diode to use J3/4/5 as the main power source, make sure that whatever is connected to pin 4 pin J3/5 can handle that voltage if using a board with the isolators.

I'll add this info to the wiki.