I was experimenting with the SYSAHBCLKCTRL0 register on my LPXpressor802 board and appear to have locked it up. Any suggestion as to how I can reset my board (I have a Segger Jlink that I can use, if necessary).
It was working okay when I had an OR in my first line
SYSCON->SYSAHBCLKCTRL0 |= 0b000000000000000000000000000001000000;
but when I changed that to a simple equal, like this
SYSCON->SYSAHBCLKCTRL0 = 0b000000000000000000000000000001000000;
and then ran the program. My suspicion is that by not using the OR I have cleared a bit that I wasn't supposed to. (I understand that removing the OR wasn't a smart thing to do... I'm trying to see if changes like this break the board before using it to teach in a classroom.)
Here is the program I was trying to run
void main(void) {
// Power up GPIO 0 unit via Bit 6 on AHB Clock Control Register
SYSCON->SYSAHBCLKCTRL0 = 0b000000000000000000000000000001000000;
// Preemptively turn off the LED on GPIO bit 8.
GPIO->SET[0] = 0b000000000000000000000000000100000000;
// Set data direction on GPIO bit 8 to Output.
GPIO->DIRSET[0] = 0b000000000000000000000000000100000000;
// Turn on the LED on GPIO bit 8.
GPIO->CLR[0] = 0b000000000000000000000000000100000000;
} // end of main
Fixed!
I recompiled my original code ( with the |= )
SYSCON->SYSAHBCLKCTRL0 |= (1UL<<SYSCON_SYSAHBCLKCTRL0_GPIO0_SHIFT);
and then selected "Debug" with the JLink as follows
Lesson learned? Always have a stand-alone debugger, like a JLink, even if the board has an onboard debugger.
all the best,
James
Hi
Thank you for your interest in NXP Semiconductor products and
for the opportunity to serve you.
Firstly, using the following code to enable the GPIO clock, however, it will disable other units' clock. For instance, they include the AHB, the APB bridge, the Arm Cortex-M0+, the SYSCON block, and the PMU, etc.
SYSCON->SYSAHBCLKCTRL0 = 0b000000000000000000000000000001000000;
Fig 1
No doubt, it will crash the MCU after doing this.
MCUXpresso provide the feature which allow the developer to to observe the changing of SYSAHBCLKCTRL0 register in the debug, I think it's just you want, please refer to MCUXpresso's user guide to enable this feature.
TIC
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Hi Jeremy,
I read through the manual (good suggestion!) and was able to use the "Attach" mode to access the registers on the board. I modified 0x40048000 (SYSAHBCLKCTRL0) to be 0x000000D7 (i.e. default value + GPIO on). I am still getting a flash writing error. Thinking that this may be because of my MCUXpresso installation, I tried programming the '802 board on my Mac, with MCUXpresso 10.1. I got the same flash writing error.
Do you have another suggestion as to what I can look at?
thanks!
James
I connected my JLink to the board (with a jumper on EXT_DBG and power applied to USB on the board). I can access the SYSAHBCLKCTRL0 register and set it to 0xD7 with the JLink, too. However, when I try to erase flash with the JLink I get an error, too. It says something about "failed to download RAMCode."
