LPC4330-Xplorer RTC Crystal

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by joohyun.seo on Tue Jul 29 17:33:42 MST 2014

I am new to use LPC43xx series MCU, and I am trying to learn using the evaluation board of LPC4330-Xplorer. Technically, the MCU attached on the board is LPC4337.

Anyhow, I was trying to run a basic example of LED blinky using Keil IDE, and I ran into some problem. In the example main C code (main.c), there is a function 'timer_delay_ms(50)' to implement the delay to turn the LED on and off. However, this line is not working. After I commented out this 'timer_delay_ms(50)' line, I checked that I can turn on or off the LED by controlling the GPIO1[11] and GPIO1[12], and everything seems working fine.

I checked the RTC crystal which is denoted as 'Y1' in the board, and I probed with the scope. It seems that it does not generate any oscillating signal at all. I checked 'Y3', the crystal oscillator of 12MHz, and it certainly generates 12 MHz signal. I further looked into the crystal 'Y1', and the number that I can see on top of the part is '24165'. However, in the schematics sheet found in the website, the part number for the crystal connected between RTCX1 and RTCX2 is ABS07-32.768KHZ-T, and it seems that this part usually have 'ABS07' on top of its part based on my search at Digikey. I feel like since there is no clock signal for the RTC, so the timer does not work at all.

(Also, I checked that VDDREG which is connected to the 3v3 power supply can provide the voltage supply to the RTC block. In this eval board, I checked the VBAT is not connected to anything else. VBAT was shorted to the 3v3 power supply, and it does not make any difference.)

Thus, I am wondering if anyone experienced this not-functional timer_delay_ms() issue? In addition, is the part '24165' for Y1 crystal right part or should it be the other part 'ABS07-32.768KHZ-T' as it is written in the schematics? I feel like many people should have done this 'blinky' example. So, please let me know if anyone experienced the same issues and know how to solve it.

I appreciate your help in advance.