ProductsMicrocontrollersSupportFAQLPC900

Frequently asked questions

LPC900 Family LPC952 FAQ

Q When trying to enter ISP mode on the LPC952 microcontroller, it does not work. What could be wrong?
A
The following flow chart shows the ISP entry:
If the 3-pulse ISP entry is used, make sure the correct signals are on the VDD and reset lines. The following diagram shows the 3 pulses on reset:
A A voltage on an IO pin can source current into the microcontroller when VDD is not supplied. This can cause the microcontroller not to get a good power-on reset signal. In this case, the ISP may not be entered with the 3 pulses on reset. Make sure when the device is powered down no IO pin has a voltage on it.
A Make sure AVDD is not supplied when VDD is 0V. The core can be powered through the AVDD when VDD is not supplied.
Q Can I use a 2-wire debug interface to program the LPC952?
A
Yes. A programming solution through the 2-wire debug interface (FS2 Debugger) is available from First Silicon Solutions.
Q When I connect the MCB950 development board, which com port is used?
A
This can vary from PC to PC. To see which com port is assigned to the USB port, check the port settings in the device manager in the system settings of the control panel. In the example below, the com port shows up as COM6.
Q When I try to connect to the FS2 console to debug the LPC952, I get the error: Incorrect CPU identification code. (error 257). What do I do?
A
Make sure the console settings are correct. Select m8051 ew-single-core, SysNav, USB, and FS2DI.
Click on Configure... and set the Tck Rate to 250000.
Q How can I see the data or SFRs when debugging?
A
In the Keil uVision memory window, use d:0x0 to see the data. The image below shows an example:
Q Can I use the same ICP programming as with the other LPC952 devices?
A Yes. ICP programming is also supported on the LPC952.
Q Can I use the 2-wire debug pins as IO when I am debugging?
A No. During debugging, the debug pins are dedicated to the debug interface and can not be used as standard IO pins.
Q Where can I download the latest drivers for the FS2 system navigator?
A
The latest firmware from FS2 can be downloaded from First Silicon Solutions (FS2).
Q Can I break during debugging on a specific address?
A
Yes. In Keil's uVision, when in debug mode, go to the Peripherals menu and select the FS2 Triggers in the trigger window. There, you can set the address to trigger a break on.
Q Can I break during debugging on specific data?
A
Yes. In Keil's uVision, when in debug mode, go to the Peripherals menu and select the FS2 Triggers in the trigger window. There, you can set-up the data to trigger a break on.
Q Can I synchronize an external scope on an event in my software with the 2-wire debug interface?
A Yes. The 2-wire debug interface has the capability to output a trigger signal with which an external scope can synchronize.
Q What are the different events that can cause a trigger event?
A Triggers can be set-up for a specific address, bank, or data. Code Read, Code Write, Xdata Read, Xdata Write, Idata Read, Idata Write, SFR Read, and SFR Write are all different events that can be triggered individually or in combination.
Q Which UART is the USB connector hooked up to on the MCB950?
A The USB connection on the MCB950 is hooked up to UART 0.
Q Which UART is the DB9 connector hooked up to on the MCB950?
A The DB9 connector on the MCB950 is hooked up to UART 1.
Q Which ADC channel is the potentiometer hooked up to on the MCB950?
A The potentiometer on the MCB950 is hooked up to AD02.
Q Is there any sample software for the LPC952's ADC using the potentiometer on the MCB950?
A
Yes. See ZIP file below for sample code.
Q Is there any software for using the P5 LEDs on the MCB950?
A
Yes. See ZIP file below for sample code.
Q How do I access extended SFRs in the Keil C compiler?
A
The XSFRs can be accessed like any other SFR in C. The addresses of the extended SFRs are defined in the header file. For example, an ADC result register on the LPC938: char xdata AD0DAT0R _at_ 0xFFFE;. When accessing the XSFR, the compiler will translate it into a MOVX command. For example, reading from AD0DAT0R:
Q Is there some sample software how to access the XSFRs and control port 5?
A
Yes, in the ZIP file, the ADCdef.h contains the definitions of the XSFRs like:
Q Can peripherals still run when the debugging of the LPC952 is halted?
A Yes. Individual peripherals can be stopped or left running by setting the appropriate bits in the FREEZE register, which is located at FFD0h in XSFR space.
Q Can I set security bits when debugging the LPC952?
A No. The security bits will lock out the debugging of the LPC952. It is recommended not to set security bits during the debugging phase of a project.
Q When I try to debug the LPC952, the console window shows that the device is not detected. What could be the cause of this problem?
A When the device has disabled the debugging in the UCFGx register, the 2-wire debugging will not work.
A When the TCK rate is set too fast, the 2-wire debugging interface may not respond correctly. A TCK rate of 250000 is recommended.
A When the reset duration of the 2 wire debugging interface is set too short, the debugging may not respond correctly. A reset duration of 100ms is recommended.
Q Is there a way to test if the FS2 system navigator may be damaged?
A Yes. The FS2 system navigator comes with a small test board that can be connected to the 10-pin header. The test command in the FS2 console will do a self-test on the debugging signals.
Q Is there an erratasheet for the LPC952?
A
Yes. You can find it easiest from our Standard ICs website search. You can also browse for it in our Support Documents section.
Q Can Flash Magic be used to program the LPC952?
A
Yes. The latest version of Flash Magic can be downloaded from www.esacademy.com/software/flashmagic. Be sure to set the correct com port that the PC has assigned to the MCB950 board in FlashMagic. See the example below:

Other Questions

If you have other questions that you would like answered, please contact us.
Standard ICs quick find
Standard ICs sections
See also