mbed NXP LPC1768

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3 related questions:


35 comments:

05 Aug 2010

The LPC1768 datasheet can be found at http://www.nxp.com/documents/data_sheet/LPC1768_66_65_64.pdf

01 Sep 2010

Thats an old datasheet. Here is a new one: Rev. 6 — 25 August 2010 http://ics.nxp.com/products/lpc1000/datasheet/lpc1763.lpc1764.lpc1765.lpc1766.lpc1767.lpc1768.lpc1769.pdf

17 Oct 2010

I have a question, the lpc1768 datasheet states (on page 45, static characteristics) that the I/O pins can drive +/- 4mA, not 40mA. I checked for an errata sheet and found nothing about this. Is the 40mA spec stated above wrong? Or the datasheet? Could you please clarify? Thanks!

Regards, Alex

19 Oct 2010

These are the lines for data you are looking for:

/media/uploads/rostrum/sc_output_current.png

Alejandro Celery wrote:

I have a question, the lpc1768 datasheet states (on page 45, static characteristics) that the I/O pins can drive +/- 4mA, not 40mA. I checked for an errata sheet and found nothing about this. Is the 40mA spec stated above wrong? Or the datasheet? Could you please clarify? Thanks!

Regards, Alex

27 Oct 2010

Short-circuit current values are not the same as drive capability. Most circuits you'd want to drive will require some voltage as well as current to do something useful. Also these are maximum values; actual values may be significantly lower.

From the data that Alex refers to you can determine that the output resistance of the I/O driver is at most 100 ohms as long as you don't draw more current than 4 mA / output voltage drop is less than 0.4V. However, you cannot just assume this resistance will be constant at stronger loads, at some higher voltage drop the output MOSFET may saturate.

In short, although you may be able to draw considerably more than 4 mA from an output, you can't really count on anything beyond what is specified.

Best regards, Simon

14 Nov 2010

Question...

in schematic diagram you can note that LINK_LED and SPEED_LED fron net i/f are wired to mbed i/f ic... I would like to read them to mimic standard ethernet RJ45 leds...

How can I access them?

26 Nov 2010

Hi, is there any information on MBED-IF01 (IC1), something like a datasheet. No doubt it is a FPGA with a custom configuration for the mbed.

What is needed is:
MBED-IF01 purpose and how it achieves that purpose in the mbed environment.
i.e.

  • Inputs TARGET_RESET_REQ1 and TARGET_RESET_REQ2 are connected via "or" logic to output TGT_NRESET (-> input LPC1768 NRESET)
  • The RESET is connected "+3.3V". To reset power cycle the mbed.
  • CFG lines? where is each of 6 rectangular pads? is CFG6 -X the large VIA test-point? what does it provide?
  • IO lines?
  • NC lines?
  • FLASH lines?
  • etc.

The information on the raw unconfigured underling FPGA(??) device is NOT that useful.

26 Nov 2010

It's not FPGA, it's another ARM chip (LPC2368 IIRC). You can find some info here.

13 Dec 2010

which is the max load I can drive with the 3.3 regulated output? My GPS application consumes around 120mA but this seems to be to much for the LPC1768. The datasheet of the used LD1117S33 promised up to 800mA, so I was hopeful to drive my app directly, but now I need obviously an external power supply :-(

15 Dec 2010

Igor Skochinsky wrote:

It's not FPGA, it's another ARM chip (LPC2368 IIRC). You can find some info here.

The mbed interface chip you are referring to is a LPC2148 and is on the bottom of the board. The old mbed used LPC2368 instead of the now LPC1768 for the target.

25 Feb 2011

Can someone clarify whether I need to use pull-up resistors or not? It says above that the pull-up resistors are on board and so can be driven by an open collector but on the I2C page it says pull-up resistors are required. Is that something peculiar to I2C?

Thanks

04 Jun 2011

Errata - There is also a LPC1768 minor bugs datasheet , http://ics.nxp.com/support/documents/microcontrollers/pdf/errata.lpc176x.pdf

04 Jul 2011

The reference card I received with the mbed shows Vin to be 4.5V - 14.0V In, but the above shows 4.5V - 9.0V In. Which one is correct? I also have an older mbed that says 9.0V on the quick reference card. Has there been an update that allows Vin to be up to 14V?

24 Dec 2011

I read from http://www.nxp.com/products/microcontrollers/cortex_m3/lpc1700/LPC1768FBD100.html that the chip itself have several timers, but i can't find it on mbed NXP LPC1768 board. does that mean it's not connected to a break out pin?

24 Dec 2011

The timers are internal

23 Mar 2012

Can we use the microcontrollers USB port (pins 31, 32) as a USB device? Or does it only works as a USB host?? Thanks in advance, Pedro

23 Mar 2012

USB port p31/p32 can work in both host and devicemode. Examples are in the cookbook.

23 Mar 2012

@Wim: ok, thanks! I'll look into it this week end.

30 Apr 2012

Hooops... Just want to take a look for some new before ordering just 2 more and sorry that i have to see the supplyvoltage is decreased in its range from max.14,5Vin to max.9,0Vin. That isn`t usefull i think...When it was changed and why it was? The wide range of the supplyvoltage have made the mBed very interesting for some things...

30 Apr 2012

This forum post discusses the change in more detail: http://mbed.org/forum/mbed/topic/127/?page=1#comment-451

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