New LPC4337 PCB Design, JTAG Target not found

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by avr458 on Mon Apr 08 16:16:11 MST 2013


 I have since received and populated my new design with the bare minimum of components needed to connedt the target chip (LPC4337JBD144) to a JTAG programming interface. As of yet I still have not yet gotten it to be recognized as a JTAG traget. My previous design had many errors mostly with the JTAG connector (usign 10 pin Cortex Debug connector) lacking pullups on each pin as well as ESD protection the abscense of jumperable boot select pins, added bypass caps to all voltage inputs on all devices, and the absence of jumperable DBGEN and TRST pins with the option to pull either pin high or low. When I assembled my new design I was careful to solder at a low temperature (260C) keeping the board under heat for the shortest time periods I could possibly allow while still make sure everything reflowed together correctly. When assembling the board I did it in stages, I first assembled the power supply and got it functioning without shorts before proceeding with further assembly. After the powersupply was assembled I proceeded to populated the rest of the PCB, I added all the bypass capacitors, JTAG connector circuitry, boot jumpers, and lastly the LPC4337JBD144 itself. Before powering on the board I manually used a hot air reflow reworking station and a fine tip soldering iron to manually remove all excess solder from all coponents, this was done to eliminate short circuits and to ensure that every single component was secured in the correct orientation to the pads on the PCB. I should note that all soldering was done at 260C for the shortest possible time that could be allowed. Lastly I fluxed down all solder points of the PCB and gave it a once over with the hot air gun to make sure everything was attached and secured to the PCB. When I powered it on for the first time everything went well no short circuits or anything.

I have since been attempting to program it with LPCXpresso 4.3 on Mac OS X 10.8.3 using an LPC-Link and a sample project made for the LPC4337JBD144 that an NXP tech support representative gave me to use for testing. My protocol for programming the target is to compile the LPC4337 project using the included library project (NOTE: I made sure paths and symbols are configured correctly, and the correct target is selected for both the sample project and the library project) I then use the JTAG/Debug download tool (chip symbol in the top tool bar) to attempt a download tot he target, I have the correct flash driver selected and the right memory address configured.   I have not been able to successfully program the chip with the JTAG programmer, considering that the hardware configuration is correct I am running out of ideas as to how I can get the chip to program. Does anyone know anyting I could be doojgn wrong? Doing a little investigation into the reference boards and the specification in the datasheet for the LPC43xx family I have discovered that they are all using conflicting JTAG header configurations for the 10 pin cortex header. Some designs have pullups on each of the data pins for the JTAG connector, the schematic provided by an NXP rep has all pins pulled down, the Hitex and Keil boards have a combination of pulling pins low and high and they are both different. Fortunately the design of my PCB will allot me to cleanly modifiy the pullups I currently have on the JTAG connecotr into pulldowns or any combination of pullups and pulldowns very easily what I would like to know what is the correct configuration because the three sources which I consider official (NXP, Keil/ARM,Hitex) are all completely different from eachother.


Here is a link to the schematic and board printouts for my design