topic Re: 1769 refuses to start in LPCXpresso IDE

1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:06 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 05:59:03 MST 2011
So after a couple months testing on breadboards with the help of breakouts, I've made a PCB for my 1769 project.

In this board, I only use 1x 12Mhz crystal.
There is no 32768khz xtal2.

For some strange reason, when I power up the board from the onboard USB socket -> into the onboard 5v to 3v3 LDO to power the board, the processor refuses to start.

I have to do a manual reset ( RESET_N to GND ) and then the board starts.

When it is already powered up from USB and I re-program from the JTAG/SWD, it starts normally and works normally as if I was still using the original LPCXpresso board and breakouts.

The pins relevant are, as far as I know, all connected properly:
+3v3 : Pins 10, 12, 19, 28, 42, 54, 71, 84, 96
GND: Pins 11, 15, 31, 41, 55, 72, 83, 97

Then also...
1) a 10K resistor from pin 4 TRST_N (pin 4) to +3v3
2) a 10K resistor from pin 17 RESET_N (pin17) to +3v3

Where could I be wrong, and what to test to know if the board is holding in reset for some reason.

Last but not least. Pullups on JTAG are not fitted.

Edit: fitted a 100nF to ground on the RESET_N, to try a delay.... still no joy.

Thanks !!

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:07 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Jul 24 06:39:19 MST 2011
Pin13 :confused:
Pin 53 :confused:

LDO circuit ?

JTAG connected or SWD connected ?

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:08 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 07:29:32 MST 2011
Pin 13 is not connected to anything.
Pin 53 has a push switch connected to it. Pin 53 is tied to high with a 10K pullup and also a 100nf for debounce.
This serves as UART0 bootloader mode entry if kept pressed on powerup. ( FlashMagic )

LDO... LM1117 3v3. 10uf on input, 10uf+100nf on output.

Quote:
JTAG connected or SWD connected ?

I'm using an extension of the LPCXpresso programming pins into my board.

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:09 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Jul 24 07:42:58 MST 2011
Did you check if all pins are really connected ?

Did you check your crystal (could be a little bit slow) and it's caps ?

Does this problem occur with and without connected SWD ?

Does this problem occur if you use a 5V power supply instead USB ?

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:09 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 13:29:08 MST 2011
Hi Zero, Thanks for your reply.

>>>Did you check if all pins are really connected ?
I did again a thorough check on all supply, gnd, RESET_N and TRST_N, and also their pullups. 100% good.

>>>Did you check your crystal (could be a little bit slow) and it's caps ?
The crystal timing confirmed 12.000Mhz ( same components from the LPCXpresso board )

>>>Does this problem occur with and without connected SWD ?
Absolutely. With and without... same No Startup, unless I manually reset RESET_N, where it then starts up as normal.
I've even tried some delays in code, on startup, just after SystemInit. No Joy.

>>>Does this problem occur if you use a 5V power supply instead USB ?
Yes. USB supply, or 5volt into the regulator input produce the same issue.

Hmmm....

What can I do to use RSTOUT_N as a clue to this problem ??
Any thing in code that I can use ??

Debugging to try to see what;s happening is not helpful, because just after a programming, the board always starts perfectly.

To me it seems that something is causing the board to jump into bootloader mode.
Which is the most helpful pdf regarding bootloader on the 1769 ??

Thanks.

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:10 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Jul 24 13:45:02 MST 2011

Quote: Wenzu
To me it seems that something is causing the board to jump into bootloader mode.

Then scope pin 53 to control if it's low too long :confused:

Or use FlashMagic to control if you're in ISP mode :)

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:10 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 13:48:42 MST 2011
Ok Thanks.. will do.
I'll try removing the de-bounceing 100nf as well.

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:11 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 13:51:54 MST 2011
That fixes it.
Thanks Zero.
Removing the 100nF from Pin53-to-GND makes the board start reliably.

Sorted. Another 2 beers for you !!:):):)

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:12 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 13:54:43 MST 2011
Replaced cap with 10nf and starts reliably. !! Happy !!

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:12 GMT

Content originally posted in LPCWare by Ex-Zero on Sun Jul 24 14:01:22 MST 2011
Increasing Reset pullup to something like 20k should work also (with 10k / 100nf @ pin53) :eek::eek:

Re: 1769 refuses to start

lpcware — Thu, 16 Jun 2016 01:55:13 GMT

Content originally posted in LPCWare by Wenzu on Sun Jul 24 14:08:44 MST 2011
Of course.... this will delay startup. Thanks for pointing it out.
But I prefer to have the MCU start up as fast as possible, Then I check debounce in code.
I really would like to Thank You for your help. I learn something new everytime. This is best education one can have.