linux-libre-firmware/atusb/board_rzusb.c

/*
 * fw/board_rzusb.c - RZUSB Board-specific functions (for boot loader and application)
 *
 * Written 2016 by Stefan Schmidt
 * Copyright 2016 Stefan Schmidt
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */


#include <stdbool.h>
#include <stdint.h>

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/boot.h>

#define F_CPU   8000000UL
#include <util/delay.h>

#include "usb.h"
#include "at86rf230.h"
#include "board.h"
#include "spi.h"
#include "usb/usb.h"

static bool spi_initialized = 0;

void reset_rf(void)
{
	/* set up all the outputs; default port value is 0 */

	DDRB = 0;
	DDRC = 0;
	DDRD = 0;
	PORTB = 0;
	PORTC = 0;
	PORTD = 0;

	OUT(LED);
	OUT(nRST_RF);   /* this also resets the transceiver */
	OUT(SLP_TR);

	spi_init();

	/* AT86RF231 data sheet, 12.4.13, reset pulse width: 625 ns (min) */

	CLR(nRST_RF);
	_delay_us(2);
	SET(nRST_RF);

	/* 12.4.14: SPI access latency after reset: 625 ns (min) */

	_delay_us(2);

	/* we must restore TRX_CTRL_0 after each reset (9.6.4) */

	set_clkm();
}

void led(bool on)
{
	if (on)
		SET(LED);
	else
		CLR(LED);
}

void set_clkm(void)
{
	/* switch CLKM to 8 MHz */

	/*
	 * @@@ Note: Atmel advise against changing the external clock in
	 * mid-flight. We should therefore switch to the RC clock first, then
	 * crank up the external clock, and finally switch back to the external
	 * clock. The clock switching procedure is described in the ATmega32U2
	 * data sheet in secton 8.2.2.
	 */
	spi_begin();
	spi_send(AT86RF230_REG_WRITE | REG_TRX_CTRL_0);
	spi_send(0x10);
	spi_end();

	/* TX_AUTO_CRC_ON, default disabled */
	spi_begin();
	spi_send(AT86RF230_REG_WRITE | 0x05);
	spi_send(0x80);
	spi_end();
}

void board_init(void)
{
	/* Disable the watchdog timer */

	MCUSR = 0;		/* Remove override */
	WDTCSR |= 1 << WDCE;	/* Enable change */
	WDTCSR = 1 << WDCE;	/* Disable watchdog while still enabling
				   change */

	CLKPR = 1 << CLKPCE;
	/* We start with a 16 MHz/8 clock. Put the prescaler to 2. */
	CLKPR = 1 << CLKPS0;

	get_sernum();
}

void spi_begin(void)
{
	if (!spi_initialized)
		spi_init();
	CLR(nSS);
}

void spi_off(void)
{
	spi_initialized = 0;
	SPCR &= ~(1 << SPE);
}

void spi_init(void)
{
	SET(nSS);
	OUT(SCLK);
	OUT(MOSI);
	OUT(nSS);
	IN(MISO);

	SPCR = (1 << SPE) | (1 << MSTR);
	SPSR = (1 << SPI2X);

	spi_initialized = 1;
}

void usb_init(void)
{
	USBCON |= 1 << FRZCLK;		/* freeze the clock */

	/* enable the PLL and wait for it to lock */
	/* TODO sheet page 50 For Atmel AT90USB128x only. Do not use with Atmel AT90USB64x. */
	/*  FOR 8 XTAL Mhz only!!! */
	PLLCSR = ((1 << PLLP1) | (1 << PLLP0));
	PLLCSR |= 1 << PLLE;
	while (!(PLLCSR & (1 << PLOCK)));

	UHWCON |= (1 << UVREGE);

	USBCON &= ~((1 << USBE) | (1 << OTGPADE));		/* reset the controller */
	USBCON |= ((1 << USBE) | (1 << OTGPADE));

	USBCON &= ~(1 << FRZCLK);	/* thaw the clock */

	UDCON &= ~(1 << DETACH);	/* attach the pull-up */
	UDIEN = 1 << EORSTE;		/* enable device interrupts  */
//	UDCON |= 1 << RSTCPU;		/* reset CPU on bus reset */

	ep_init();
}

void board_app_init(void)
{
	/* enable timer input capture 1, trigger on rising edge */
	TCCR1B = (1 << ICES1);
	TIFR1 = (1 << ICF1);
	TIMSK1 = (1 << ICIE1);
}