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USB Standard Multilink Universal works Intermittently
Thiago W. Aug 5, 2015 at 04:13 PM (16:13 hours)
Staff: Takao Y.

  • We have in our company several USB Standard Multilinks Universal that can't provide power to the MCU.

    We use the DSC family of microcontrollers from Freescale that works on 3.3V, more specifically MC56F84XXX , for solve the problem of power supply we connect a 3.3V regulator on 5.0V USB power (LM7833) and connect to a PIN 11 of the JTAG DSC connector.

    We use the PROGDSC from PEMMICRO software, and the Flashing programming process are intermittently, several times I open the PROGDSC and flash normally, other times (most times), I open the PROGDSC, choose Standard Multilink in a list click in "OK" and the message : "The target MCU is not responding. Please turn MCU power off, turn MCU power on, and then click ok. This will attempt to enter debug mode" the image is below:

    After click several times on RE - Reset Chip , sometimes all the list is showed and I can flash the device with success.

    I already checked the 3.3V level on multimeter and all it's ok. I checked all JTAG pins too, I tried with another boards too.

    Do you have any idea why this problem occours? I can flash with success the same boards or anothers in aproximadely 30 percents of cases.

    What is the correct way to use PEMICRO devices as multilink standard, cyclone max and another that can't provide power supply to the MCU? How can I provide external power supply ? Must I only connect the external power supply to GND and VCC on JTAG pins or need I cut off the power supply to reset before flash to do a reset? Must I sincronize the cut off process of reset with my external power supply to cut off?


  • Greetings,

    The VDD or VCC line on the JTAG pin must be the voltage of the chip. So is this 3.3V regulator connected to the chip, or just the JTAG VCC line? Or more importantly, is the VCC on JTAG a direct connection to VDD on the chip? This VCC line is used as a reference voltage for the other signals like TDI and TDO. If VCC is 3.3 V, then a high signal for TDI is 3.3V instead of 5V.

    In most cases where the P&E interface cannot provide power, the user uses external power to their board. That external power is regulated and allocates power to the chip. Then that VCC of the chip is read by the multilink for reference. (It also needs some current of about 100mA from the chip to be able to power a few buffers).

    Takao Yamada

  • My external 3.3V is connected on PIN11 of PORT A of Multilink HEADER and my external GND on PIN 2, 4, 6 and 12 on PORT A of Multilink Header.

    The problem is that sometimes works and I can flash normally using this configuration, other times, not, please read my text above complete and view the link of the image.

  • Greetings,

    I did read the text completely and saw the picture. But if the problem is intermittent, then there could be a hardware problem with power.

    A test I want you to do is use one board and try flash programming it 5 times consecutively. Does it only fail the first time? Does it fail only after the first time? Is the chip blank when you first try to connect? Try connecting when the chip is not blank.

    Are you using any custom hardware between the P&E interface to the chip, like custom ribbon cables, adapters, watchdog, or reset circuitry?

    Takao Yamada

    • 1) Usually it's fail at the first time, and works in second time, but not always, sometimes it works on fifth time for example.

      2) The problem occours when the chip is blank too. When the chip isn't blank the problem is equal.

      3) My custom hardware is the image below, When I connect a 3.3V regulator at the VCC pin of de flash programmer, please see bellow:

  • Greetings,

    I did not realize this customization is on the multilink itself! I highly suggest not doing this. You will void the warranty on the multilink as any damage will not be due to manufacturing. The multilink universal does not have the same power protection or the capability to provide power to target.

    Why are you not powering up your board externally? Why not just purchase the multilink FX? Your implementation is a hacked solution and I cannot help a customer who modifies the multilink.

    Takao Yamada

  • 1) Ok, I know, But you can see that the multilink have that 18 exposed PIN, what is utility of these exposed PINs?

    2) I know that I must use Multilink FX for power supply, but if you sell Multilink Standard and I should develope my external power supply, you must have a official document that shows and recommend how I can connected my power externally power to the Multilink Standard.

    Please, how can I connected my external power to Multilink Standard? Do you have any document? Do you have any recommendation? If you sell this product, you must provide a orientation. Must I only connected my external VCC to JTAG VCC and GND PINS of PORT A Multilink Header? If not, how? Could you explain? I didn't found any document explaing...

    Best Regards.

  • Greetings,

    1) The exposed pins are used to program the multilink. We use a proprietary setup to be able to program and debug the unit.

    2) Remove the multilink out of the equation for a minute. How do you plan on powering your board when it is out of prototyping stage? Your board needs to be self powered. That external power to your board needs to be able to power up the chip and all other peripherals. THIS is the power that needs to be provided when using the multilink. Powering the unit via the multilink is only for convenience and customers should buy the multilink universal FX to do so.

    We will not document or suggest to customers how to modify the multilink to provide power.

    Takao Yamada

    • 1) OK.

      2) So, think, my own board is powered yes, how? The VCC that supply my MCU in my own board is the SAME VCC that JTAG PIN11 , do you agree? Consequently my VCC of my own board of my MCU is the SAME of the JTAG PIN11. A can't understand how can I connect my external power and supply my MCU avoiding connected to the PIN11 of JTAG connector, because is the same.

      3) It's impossible using external power supply with Standard Multilink, avoiding that I use the same GND between booth units. Please explain better.

  • Greetings,

    I am sorry but I cannot help you. I do not want any customers attempting to do this so I cannot talk further about this topic. Any modifications is at your own risk and results will vary. We cannot guarantee any success or flash programming or debugging if the unit has been modified.

    Takao Yamada

    • We bought several Standard Multilinks and several Cyclone MAXes from you. We won't modify anymore and will use in a original way.

      Please, we now that both don't have power supply. We wish to use a external power supply, but we don't have any idea how can we external supply the MCU and put in the same reference (GND) the flash programmer and the external power supply.

      Could you validate my external power supply to Cyclone MAX with the schematic below?

  • Greetings,

    You should contact Freescale about recommendations on how to wire up the power circuitry for your chip. Usually the reference manual provides tips about this, and you can also look at Freescale's evaluation design to replicate their recommended connections:

    Takao Yamada

  • Yes,I know these designs and we agree with you, our design is equal of evaluation design in JTAG header , when the JTAG PIN11 is VCC and PIN2,4,6  are GND.

    The question that I want that you understand is that JTAG PIN11 in Cyclone MAX and Multilink standard are VCC too and JTAG PIN2,4,6 in Cyclone MAx And Multilink standard are GND too, therefore I should connect between them. Could you explain how I can flash without use the same GND and VCC between external power supply and Cyclone Max and Multilink Standard.

    For simplify my doubt, could you explain doing a simple draw (draw by hand) , between the connections of the JTAG VCC and GND of Multilink Standard and Cyclone MAX and the external power supply and MCU?

    Unfortunnatelly I can't understand how can I do a flash without using the same GND and VCC.

  • Greetings,

    Do you have news about the doubt above?

  • Greetings,

    Again, VCC and GND found on the JTAG is the same on the P&E hardware and the chip. If the external power supply is directly connected to the chip, then that is the same connection, however that is not a good board design. You probably want voltage regulators, capacitors between power and ground to provide stable power, and other basic power protection. If the naming convention is confusing you, then just rename your signals! VCC_TGT, GND_TGT, or VCC_JTAG, GND_JTAG. All that the P&E interface cares about is the voltage on the chip. Just do not derive that power from P&E's USB connection.

    Takao Yamada

  • Yes I know, but if you understand, GNT_TGT must be connected to GND_JTAG, without this it's impossible to work, do you agree?

    Please, check my design of power supply and see if it's correct:

  • Greetings,

    Yes, the target's GND needs to be the same as GND JTAG. I do not know how many times I have to repeat myself.

    I am not here to consult whether your board and power supply is correct.

    Takao Yamada

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