Sanity check

[lpcware]

Content originally posted in LPCWare by mhjerde on Tue Mar 23 16:35:31 MST 2010
I've been struggled for a while with the poor drivers and example code for the LPC1343. I'm starting to think I've seriously missed something... The code examples accompanying the latest version of the IDE are marked "Preliminary version" and dated 2008.

Where can I find the latest drivers and examples?

M

[lpcware]

Content originally posted in LPCWare by rmteo on Wed Mar 24 18:46:06 MST 2010
In your position (building a prototype that hopefully will lead to mass production and sales of a meaningful number of MCU's), couldn't you get in touch with your local NXP office and have them assign an FAE to answer any specific questions you may have?

[lpcware]

Content originally posted in LPCWare by mhjerde on Wed Mar 24 16:56:33 MST 2010
Hi CodeRedSupport, thanks for your reply.

The lack of attention to detail that leaves "Preliminary" and "2008" in the header is evident throughout the rest of the code and examples.
Please contemplate for a minute "what is the purpose of a code example?" One typical purpose would be to convey information as clearly and understandable as possible to someone who is unfamiliar with it.

And then have a look at at this typical example from the lpcxpresso kit. There is barely commenting at all and plenty of "magic numbers". In order to understand the code below you would have to go through it line by line with the UM in hand to try and deconstruct what is going on. I'm sure you can easily see for yourself a number of other issues with the code below.

I believe we're in the target group for the LPCxpresso. We're new to the part, we're building a prototype that hopefully will lead to mass production and sales of a meaningful number of MCU's. I thought lpcxpresso would be a quick way to get up and running, but that was a mistake. The xpresso part of the name does not seem to refer to speed of development, but rather to the amount of coffee you have to drink while trying to get the thing running.

---

Quote:

/*****************************************************************************
** Function name:I2CInit
**
** Descriptions:Initialize I2C controller
**
** parameters:I2c mode is either MASTER or SLAVE
** Returned value:true or false, return false if the I2C
**interrupt handler was not installed correctly
**
*****************************************************************************/
uint32_t I2CInit( uint32_t I2cMode )
{
  /* It seems to be bit0 is for I2C, different from
  UM. To be retested along with SSP reset. SSP and I2C
  reset are overlapped, a known bug, for now, both SSP
  and I2C use bit 0 for reset enable. Once the problem
  is fixed, change to "#if 1". */
#if 1
  LPC_SYSCON->PRESETCTRL |= (0x1<<1);
#else
  LPC_SYSCON->PRESETCTRL |= (0x1<<0);
#endif
  LPC_SYSCON->SYSAHBCLKCTRL |= (1<<5);
  LPC_IOCON->PIO0_4 &= ~0x3F;/*  I2C I/O config */
  LPC_IOCON->PIO0_4 |= 0x01;/* I2C SCL */
  LPC_IOCON->PIO0_5 &= ~0x3F;
  LPC_IOCON->PIO0_5 |= 0x01;/* I2C SDA */

  /*--- Clear flags ---*/
  LPC_I2C->CONCLR = I2CONCLR_AAC | I2CONCLR_SIC | I2CONCLR_STAC | I2CONCLR_I2ENC;   

  /*--- Reset registers ---*/
#if FAST_MODE_PLUS
  LPC_IOCON->PIO0_4 |= (0x1<<9);
  LPC_IOCON->PIO0_5 |= (0x1<<9);
  LPC_I2C->SCLL   = I2SCLL_HS_SCLL;
  LPC_I2C->SCLH   = I2SCLH_HS_SCLH;
#else
  LPC_I2C->SCLL   = I2SCLL_SCLL;
  LPC_I2C->SCLH   = I2SCLH_SCLH;
#endif

  if ( I2cMode == I2CSLAVE )
  {
LPC_I2C->ADR0 = PCF8594_ADDR;
  }   

  /* Enable the I2C Interrupt */
  NVIC_EnableIRQ(I2C_IRQn);

  LPC_I2C->CONSET = I2CONSET_I2EN;
  return( TRUE );
}

---

Contrast the above to a typical snippet from one of NXP's competitors:

---

Quote:

//
//! Initializes the I2C Master block.
//!
//! \param ulBase is the base address of the I2C Master module.
//! \param ulI2CClk is the rate of the clock supplied to the I2C module.
//! \param bFast set up for fast data transfers
//!
//! This function initializes operation of the I2C Master block.  Upon
//! successful initialization of the I2C block, this function will have set the
//! bus speed for the master, and will have enabled the I2C Master block.
//!
//! If the parameter \e bFast is \b true, then the master block will be set up
//! to transfer data at 400 kbps; otherwise, it will be set up to transfer data
//! at 100 kbps.
//!
//! The peripheral clock will be the same as the processor clock.  This will be
//! the value returned by SysCtlClockGet(), or it can be explicitly hard coded
//! if it is constant and known (to save the code/execution overhead of a call
//! to SysCtlClockGet()).
//!
//! This function replaces the original I2CMasterInit() API and performs the
//! same actions.  A macro is provided in <tt>i2c.h</tt> to map the original
//! API to this API.
//!
//! \return None.
//
//*****************************************************************************
void
I2CMasterInitExpClk(unsigned long ulBase, unsigned long ulI2CClk,
                    tBoolean bFast)
{
    unsigned long ulSCLFreq;
    unsigned long ulTPR;

    //
    // Check the arguments.
    //
    ASSERT((ulBase == I2C0_MASTER_BASE) || (ulBase == I2C1_MASTER_BASE));

    //
    // Must enable the device before doing anything else.
    //
    I2CMasterEnable(ulBase);

    //
    // Get the desired SCL speed.
    //
    if(bFast == true)
    {
        ulSCLFreq = 400000;
    }
    else
    {
        ulSCLFreq = 100000;
    }

    //
    // Compute the clock divider that achieves the fastest speed less than or
    // equal to the desired speed.  The numerator is biased to favor a larger
    // clock divider so that the resulting clock is always less than or equal
    // to the desired clock, never greater.
    //
    ulTPR = ((ulI2CClk + (2 * 10 * ulSCLFreq) - 1) / (2 * 10 * ulSCLFreq)) - 1;
    HWREG(ulBase + I2C_O_MTPR) = ulTPR;
}

---

[lpcware]

Content originally posted in LPCWare by wrighflyer on Wed Mar 24 07:09:42 MST 2010

---

Quote: CodeRedSupport
I am sorry that you are having problems with the lpcxpresso examples.

---

Great explanation - just a bit of a shame that the Getting Started guide that comes with the Xpresso doesn't actually explain this. I puzzled for ages to know how the "no USB" pack of examples differed from the other one and which one I should use. Seems it should have been both (for the time being). Can I suggest that until (1) is consumed into (2) that you add a note to the PDF?

[lpcware]

Content originally posted in LPCWare by CodeRedSupport on Wed Mar 24 02:13:46 MST 2010
I am sorry that you are having problems with the lpcxpresso examples.

[U][B]Available examples[/B][/U]

There are actually a number of slightly different examples available. When you install the lpcxpresso ide, the built in examples directory for your part (in your case LPC13xx) will contain:

[U]1) LPCXpresso1343.zip[/U]
This is a small set of examples aimed mainly at those who are using only the LPCXpresso processor card itself. Thus they are largely various ways of controlling the flashing of the LED on the board. The code base for this is similar, but currently not identical, to the equivalent code in 2). Over time, we actually expect that these examples will merge into 2).

[U]2) LPCXPresso1343_v<num>_NoUSB.zip[/U]
This is a much more comprehensive set of examples which exercise many more of the peripherals of the LPC13xx - but many of them rely upon you having additional hardware connected to the processor card. The "NoUSB" here reflects that some of NXPs USB examples are not included (due to copyright issues which we hope to solve shortly) - see below for more information.

[U]3) CMSISv1p30_LPC13xx.zip[/U]
This simply contains the CMSIS files for your part. This zip is included so that if you create a new project in a new workspace, you can easily import the CMSIS library project without importing all the other lpcxpresso examples.


In addition, the latest versions of the main examples are always available, as rmteo states, from NXP's website at:

http://ics.nxp.com/support/lpcxpresso/

The version of the examples posted here also includes all of the USB related example code.

A further set of LPCXpresso examples are available for those LPCXpresso users who purchase the LPCXpresso baseboard from Embedded Artists. More details of this can be found at:

http://www.embeddedartists.com/products/lpcxpresso/xpr_base.php?PHPSESSID=4lpt37b45erabcpdsqctaf28t1


NXP also have a variety of other example code available for the LPC11/LPC13 (and LPC17) from their website at:

http://ics.nxp.com/support/documents/microcontrollers/

Not all of these provide LPCXpresso IDE (RedSuite) projects, but in these cases you should be able to import the source code into projects you create yourself without too many problems.

[U][B]Preliminary status[/B][/U]
Currently, a lot of the examples do indeed appear to have headers that suggest they are of preliminary status, and were written in 2008. Please be assured that this is not really the case, and I believe is mainly down to cut'n'paste of the headers and some of the base code from example code for previous LPC microcontrollers. We will investigate with NXP getting these headers updated.

[U][B]Problems with drivers / examples[/B][/U]
Please be assured that if you can post actual details, CodeRed and NXP will do our best to assist you with issues that you may be seeing. Over time, we will also continue to examine our example offering and make improvements where possible.

Regards,

CodeRedSupport.

[lpcware]

Content originally posted in LPCWare by rmteo on Tue Mar 23 16:40:10 MST 2010
Have you looked here (examples are dated Feb 4, 2010) http://ics.nxp.com/support/lpcxpresso/
[U][/U]http://http://knowledgebase.nxp.com/support/lpcxpresso/zip/lpc1343.examples.zip