8 years, 9 months ago.

We hope you like it!

Not quite Mbed style drag and drop programming, however as the FRDM-K20D50M board has ceased production, this does fill the gap for the K20 MCU. Double the Flash/RAM and faster!

The USB serial mode does work with the standard Mbed code. This is a test that includes a check for adding the RTC crystal:

https://developer.mbed.org/teams/CommunityContributors/code/USBSerial-RTC-HelloWorld/

After much discussion it was decided, in order to facilitate code transportation between Freescale platforms we would keep the same Pin names and definitions as much as possible. Using the Arduino pin conventions also makes it easier to transport code form other Mbed platform vendors that have the Arduino shield pin names.

We wanted to keep as much of the original graphic design to enable Arduino users to recognise the pin layout as this was not intended to be used on Mbed. So its a balance between the two.

Moving off the development board to a prototype board requires the standard manufacture pin manes to be there, PTC5, etc. The pin names are quite extensive and can be viewed in the MBED-SRC here:

https://developer.mbed.org/users/mbed_official/code/mbed-src/file/5e59b9938d4a/targets/hal/TARGET_Freescale/TARGET_K20XX/TARGET_TEENSY3_1/PinNames.h

Other pin name definitions could be added, whilst we would not want to change the existing defines, a simple 'pull request' via GitHub would be looked at by the Mbed team for a decision.

The CAN function is not yet supported and would gladly accept help with this.

void usb_init(void)
{
	int i;

	//serial_begin(BAUD2DIV(115200));
	//serial_print("usb_init\n");

	usb_init_serialnumber();

	for (i=0; i <= NUM_ENDPOINTS*4; i++) {
		table[i].desc = 0;
		table[i].addr = 0;
	}

	// this basically follows the flowchart in the Kinetis
	// Quick Reference User Guide, Rev. 1, 03/2012, page 141

	// assume 48 MHz clock already running
	// SIM - enable clock
	SIM_SCGC4 |= SIM_SCGC4_USBOTG;

	// reset USB module
	//USB0_USBTRC0 = USB_USBTRC_USBRESET;
	//while ((USB0_USBTRC0 & USB_USBTRC_USBRESET) != 0) ; // wait for reset to end

	// set desc table base addr
	USB0_BDTPAGE1 = ((uint32_t)table) >> 8;
	USB0_BDTPAGE2 = ((uint32_t)table) >> 16;
	USB0_BDTPAGE3 = ((uint32_t)table) >> 24;

	// clear all ISR flags
	USB0_ISTAT = 0xFF;
	USB0_ERRSTAT = 0xFF;
	USB0_OTGISTAT = 0xFF;

	//USB0_USBTRC0 |= 0x40; // undocumented bit

	// enable USB
	USB0_CTL = USB_CTL_USBENSOFEN;
	USB0_USBCTRL = 0;

	// enable reset interrupt
	USB0_INTEN = USB_INTEN_USBRSTEN;

	// enable interrupt in NVIC...
	NVIC_SET_PRIORITY(IRQ_USBOTG, 112);
	NVIC_ENABLE_IRQ(IRQ_USBOTG);

	// enable d+ pullup
	USB0_CONTROL = USB_CONTROL_DPPULLUPNONOTG;
}