Baby steps help request to start using LPC1764FBD100

lpcware · ‎06-15-2016

Content originally posted in LPCWare by jmitchel on Mon Dec 26 17:43:58 MST 2011
Hi,

I'm taking my first baby steps into ARM controller design.
I got a prototyping board fitted with an LPC1764FBD100 device.
Now I want to add the power lines and JTAG connector to get it programmed
to flash a simple LED with an LPCXpresso I already purchase.
I plan to break the LPCXpresso board into 2 pieces and use the 10 pin JTAG
connector to do the programming.

Here is first attempt at circuit diagram with LPC176FBD100 chip. The circuit diagram is at the bottom of the page:

http://www.enemygadgets.com/arm/arm1.html

Please comment to say if it will work.
If I missed anything out let me know and save me from blowing up a board! :D
Have I connected up all the power lines correctly? There seems to be a lot of them. Also a bit uncertain about the wiring of the JTAG.

I plan to power up the chip from an independent 3.3V supply and not draw
power from the USB. Is that a good idea?

Thanks for any comment.

JM

lpcware · ‎06-15-2016

Content originally posted in LPCWare by Rob65 on Wed Dec 28 08:20:16 MST 2011

Quote: jmitchel
Peak about 600V. Average is 500V.

Very good advise. I have had many problems including cables winding
around the board housing that then induce spikes on reset line.

Peak 600V is not that high.
I'd go for a 4N25 as isolation. They spec 5300V testing voltage.

It is some time ago but we made a terminal with touch screen that needed to withstand 8 kV testing (they used one of those high voltage probes to fire 8 kV spikes directly on the touch screen to test this).
We fixed this by adding small chokes (2-3 windings) and 10 pF capacitors on the pins of the touch screen controller.

If you want to know more about this, the book "Trilogy of magnetics" from Würth Electronics is a good choice. This book makes a nice (yet late) christmas gift for an electronics engineer ;).

For a one-off R&D jig, buy one of those RF tight metal cases to place your controller in - and buy some of those DB9 or DB25 or so connectors that contain built in filters. These things are not cheap but worth the money.

Regards,
[INDENT]Rob
[/INDENT]

lpcware · ‎06-15-2016

Content originally posted in LPCWare by jmitchel on Wed Dec 28 05:41:27 MST 2011

Quote: Rob65
I agree with Zero, use the FT232RL and let it provide the power to your opto isolators.

I am a bit concerned about the 'high voltage' it is connected to in the product.
How high is this voltage?

Peak about 600V. Average is 500V.

Quote: Rob65

If there are any electric signals nearby (if even on the same PCB) that can carry high voltage spikes then you may want to be a bit more elaborate on your DC decouplings. Just a simple 0.1 uF capacitor at the chip might not be enough. Use a larger capacitor at the reset switch and have the lines between switch and chip as short as possible to prevent sporadic resets. Use RF chokes on your power supply, have chokes and small capacitors on all I/O pins and - very important - adapt your PCB design to your needs.

Very good advise. I have had many problems including cables winding
around the board housing that then induce spikes on reset line.
You may notice the 1nF on the reset line - just a precaution.
This is all custom one off R&D jig stuff built in lots of modules until all the bits are working to put together the final product.

Quote: Rob65

I have a CNC controller board where the first version had just simple RC filtering on all I/Os and no special board design - from time to time the board would just reset, resulting in a hanging PC connection (and these were just high voltage spikes < 1 kV from the servo controllers).
The new board has a special choke on the USB line (I forgot the component number but it's a special USB choke from Würth Electronics), a separate section on the board with an isolated DC/DC converter and separate sections on the board for microcontroller+USB, power supply and I/O section.

Thank you for that note - I have had endless problems with USB resetting
due to the most minute leaks through paths I know not where.
Eventually I settled on 100% optical isolation and serial RS232 as the only
thing that works. Out of frustration I settled for that, but ideally I would like
a lot faster interface such as the USB taking readings running into megabytes
per second.

Quote: Rob65

Use a 4-layer PCB and make sure that the ground and power sections of your RS232, your microcontroller and your other (high voltage) electronics are strictly separated.

If by high voltage you mean [I]high [/I]voltage > 1 kV then prepare to take special attention to which opto isolators you are using UL1577 rated isolators are only for normal 3-phase main (400V) applications.

Regards,[INDENT]Rob
[/INDENT]

Thanks again Rob for the advise.

JM

lpcware · ‎06-15-2016

Content originally posted in LPCWare by Rob65 on Tue Dec 27 23:54:57 MST 2011
I agree with Zero, use the FT232RL and let it provide the power to your opto isolators.

I am a bit concerned about the 'high voltage' it is connected to in the product.
How high is this voltage?

If there are any electric signals nearby (if even on the same PCB) that can carry high voltage spikes then you may want to be a bit more elaborate on your DC decouplings. Just a simpel 0.1 uF capacitor at the chip might not be enough. Use a larger capacitor at the reset switch and have the lines between switch and chip as short as possible to prevent sporadic resets. Use RF chokes on your power supply, have chokes and small capacitors on all I/O pins and - very important - adapt your PCB design to your needs.

I have a CNC controller board where the first version had just simple RC filtering on all I/Os and no special board design - from time to time the board would just reset, resulting in a hanging PC connection (and these were just high voltage spikes < 1 kV from the servo controllers).
The new board has a special choke on the USB line (I forgot the component number but it's a special USB choke from Würth Electronics), a separate section on the board with an isolated DC/DC converter and separate sections on the board for microcontroller+USB, power supply and I/O section.

Use a 4-layer PCB and make sure that the ground and power sections of your RS232, your microcontroller and your other (high voltage) electronics are strictly separated.

If by high voltage you mean [I]high [/I]voltage > 1 kV then prepare to take special attention to which opto isolators you are using UL1577 rated isolators are only for normal 3-phase main (400V) applications.

Regards,[INDENT]Rob
[/INDENT]

lpcware · ‎06-15-2016

Content originally posted in LPCWare by jmitchel on Tue Dec 27 13:14:43 MST 2011

Quote: Zero
Don't know if you need RS232 and where this '5V' is supplied from, bit in general I would suggest to add an USB chip and let it supply 3.3V for your opto isolator :)

A simple start is a FT232RL (SSOP28) as shown here:

Schematic:
http://flic.kr/p/b2GfaT

3D CAD:
http://flic.kr/p/b2Gf8c

FT232RL:
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf

Hi Zero,

The 5V is from an independent mains adapter. The 3.3V is from the high voltage equipment's own internal power supply and it will power the ARM. Owing to high voltage, there is some distance between RS232 chip and battery powered laptop for safety. So for this project it has to be a local MAX232 doing the signal conversion with optical isolator.

I have some boards built that can take the SSOP28 FTDI chip and USB socket. Haven't fired one up yet because I've been using MCP2200 chip for a while which is very similar but with SOIC20 pin which is easy on the hand and eye for soldering.

I will try to get the LED flashing over the next day or two with CodeRed's IDE and come back and post results.

Thank you very much.

JM

lpcware · ‎06-15-2016

Content originally posted in LPCWare by Ex-Zero on Tue Dec 27 11:33:57 MST 2011
Don't know if you need RS232 and where this '5V' is supplied from, bit in general I would suggest to add an USB chip and let it supply 3.3V for your opto isolator :)

A simple start is a FT232RL (SSOP28) as shown here:

Schematic:
http://flic.kr/p/b2GfaT

3D CAD:
http://flic.kr/p/b2Gf8c

FT232RL:
http://www.ftdichip.com/Support/Documents/DataSheets/ICs/DS_FT232R.pdf

lpcware · ‎06-15-2016

Content originally posted in LPCWare by jmitchel on Tue Dec 27 10:47:26 MST 2011

Quote: Zero
Are you aware that programming / debugging is done with SWD (= 4 wires) and therefore this huge JTAG connectors are not necessary?

I didn't know about the SWD system. I just read up about it - arm specific programming/debugging system. I think I will use that to get going. So I wired the JTAG to become optional via DIL switch.

Quote: Zero

Looks OK :)
Why not? You can supply 3.3V however you want

Notes:

#1 Why are you using a 4 Mhz crystal?

A lot of samples are using a 10MHz crystal. If you want to use them without changing you clock settings a 10MHz would be the better option to start.

I have lots of 4MHz around :).
10MHz I can get next week when offices open.

Quote: Zero

#2 Forgotten pins:

Add a jumper for Reset (pin 17), ISP (pin 53) and RxD0 (pin 99) / TxD0 (pin 98). If you need to use ISP (via FlashMagic) this pins are very useful :)

All done as suggested.
I send the UART signals through an opto isolator because the equipment
it is intended for is high voltage when its put into final product.

Quote: Zero

#3 ISP pullup:

Add an external pullup (10k) for ISP (pin 53). Otherwise your Reset is faster and you switch always to ISP.

#4 SWD connection:

A working LPC-Link SWD for LPC11.. / LPC12.. / LPC13.. / LPC17.. is a simple 4-wire connection:

[LIST]
[*]Reset
[*]SWDCLK
[*]SWDIO
[*]GND
[/LIST]
Picture: http://www.flickr.com/photos/58892165@N08/5406234290/

Just connect this wires to your LPC17xx:

[LIST]
[*] Reset - Pin 17
[*] SWDCLK - Pin 5
[*] SWDIO - Pin 3
[/LIST]

Thank you for the photo - I followed advise.
The circuit diagram has been revised and uploaded again to same web page
http://www.enemygadgets.com/arm/arm1.html

Please do comment again.

If it can work, then I will get it wired up and have a go at programming it :D.

JM

lpcware · ‎06-15-2016

Content originally posted in LPCWare by Ex-Zero on Mon Dec 26 18:11:13 MST 2011

Quote: jmitchel
I plan to break the LPCXpresso board into 2 pieces and use the 10 pin JTAG connector to do the programming.

Are you aware that programming / debugging is done with SWD (= 4 wires) and therefore this huge JTAG connectors are not necessary?

Quote: jmitchel
Have I connected up all the power lines correctly?

Looks OK :)

Quote: jmitchel

I plan to power up the chip from an independent 3.3V supply and not draw
power from the USB. Is that a good idea?

Why not? You can supply 3.3V however you want :rolleyes:

Notes:

#1 Why are you using a 4 Mhz crystal?

A lot of samples are using a 10MHz crystal. If you want to use them without changing you clock settings (:confused:) a 10MHz would be the better option to start.

#2 Forgotten pins:

Add a jumper for Reset (pin 17), ISP (pin 53) and RxD0 (pin 99) / TxD0 (pin 98). If you need to use ISP (via FlashMagic) this pins are very useful :)

#3 ISP pullup:

Add an external pullup (10k) for ISP (pin 53). Otherwise your Reset is faster and you switch always to ISP.

#4 SWD connection:

A working LPC-Link SWD for LPC11.. / LPC12.. / LPC13.. / LPC17.. is a simple 4-wire connection:

[LIST]
[*]Reset
[*]SWDCLK
[*]SWDIO
[*]GND
[/LIST]
Picture: http://www.flickr.com/photos/58892165@N08/5406234290/

Just connect this wires to your LPC17xx:

[LIST]
[*] Reset - Pin 17
[*] SWDCLK - Pin 5
[*] SWDIO - Pin 3
[/LIST]