--- /dev/null
+/*
+ * Copyright © 2011 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#ifndef _AO_ARCH_H_
+#define _AO_ARCH_H_
+
+#include <stdio.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/sleep.h>
+
+#define F_CPU 8000000UL // 8 MHz
+
+/*
+ * AVR definitions and code fragments for AltOS
+ */
+
+#define AO_STACK_SIZE 116
+
+/* Various definitions to make GCC look more like SDCC */
+
+#define ao_arch_naked_declare __attribute__((naked))
+#define ao_arch_naked_define
+#define __pdata
+#define __data
+#define __xdata
+#define __code const
+#define __reentrant
+#define __critical
+#define __interrupt(n)
+#define __at(n)
+
+#define ao_arch_reboot() /* XXX */
+
+#define ao_arch_nop() asm("nop")
+
+#define ao_arch_interrupt(n) /* nothing */
+
+#undef putchar
+#undef getchar
+#define putchar(c) ao_putchar(c)
+#define getchar ao_getchar
+
+#define ao_arch_cpu_idle() do { \
+ sleep_enable(); \
+ sei(); \
+ sleep_cpu(); \
+ sleep_disable(); \
+ } while (0)
+
+#define ao_arch_critical(b) do { cli(); do { b } while (0); sei(); } while (0)
+
+#define ao_mutex_get(m)
+#define ao_mutex_put(m)
+
+void
+ao_delay_until(uint16_t target);
+
+/* We can't hit 100 Hz, but we can hit 125 */
+#define AO_HERTZ 125
+
+void
+ao_eeprom_read(uint16_t addr, void *buf, uint16_t len);
+
+void
+ao_eeprom_write(uint16_t addr, void *buf, uint16_t len);
+
+#endif /* _AO_ARCH_H_ */
--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+/*
+ * ao_spi.c
+ */
+
+#define ao_spi_get_mask(reg,mask,bus,speed) do { \
+ (reg) &= ~(mask); \
+ } while (0)
+
+#define ao_spi_put_mask(reg,mask,bus) do { \
+ (reg) |= (mask); \
+ } while (0)
+
+#define ao_spi_get_bit(reg,bit,pin,bus,speed) do { \
+ (pin) = 0; \
+ } while (0)
+
+#define ao_spi_put_bit(reg,bit,pin,bus) do { \
+ (pin) = 1; \
+ } while (0)
+
+
+#define ao_gpio_token_paster(x,y) x ## y
+#define ao_gpio_token_evaluator(x,y) ao_gpio_token_paster(x,y)
+
+#define ao_gpio_set(port, bit, pin, v) do { \
+ if (v) \
+ PORTB |= (1 << bit); \
+ else \
+ PORTB &= ~(1 << bit); \
+ } while (0)
+
+/*
+ * The SPI mutex must be held to call either of these
+ * functions -- this mutex covers the entire SPI operation,
+ * from chip select low to chip select high
+ */
+
+#define ao_enable_output(port, bit, pin, v) do { \
+ ao_gpio_set(port, bit, pin, v); \
+ ao_gpio_token_evaluator(DDR,port) |= (1 << bit); \
+ } while (0)
+
+
+void
+ao_spi_send_bus(void __xdata *block, uint16_t len) __reentrant;
+
+void
+ao_spi_recv_bus(void __xdata *block, uint16_t len) __reentrant;
+
+#define ao_spi_send(block, len, bus) ao_spi_send_bus(block, len)
+#define ao_spi_recv(block, len, bus) ao_spi_recv_bus(block, len)
+
+void
+ao_spi_init(void);
+
+#define ao_spi_get(bus, speed)
+#define ao_spi_put(bus)
+
+#define ao_spi_init_cs(port, mask) do { \
+ PORTB |= (mask); \
+ DDRB |= (mask); \
+ } while (0)
+
+/* I2C */
+
+void
+ao_i2c_get(uint8_t i2c_index);
+
+uint8_t
+ao_i2c_start_bus(uint8_t address);
+
+#define ao_i2c_start(i,a) ao_i2c_start_bus(a)
+
+void
+ao_i2c_put(uint8_t i2c_index);
+
+uint8_t
+ao_i2c_send_bus(void *block, uint16_t len, uint8_t stop);
+
+#define ao_i2c_send(b,l,i,s) ao_i2c_send_bus(b,l.s)
+
+uint8_t
+ao_i2c_send_fixed_bus(uint8_t value, uint16_t len, uint8_t stop);
+
+#define ao_i2c_send_fixed(v,l,i,s) ao_i2c_send_fixed_bus(v,l.s)
+
+uint8_t
+ao_i2c_recv_bus(void *block, uint16_t len, uint8_t stop);
+
+#define ao_i2c_recv(b,l,i,s) ao_i2c_recv_bus(b,l.s)
+
+void
+ao_i2c_init(void);
+
+/* notask.c */
+
+uint8_t
+ao_sleep(__xdata void *wchan);
+
+void
+ao_wakeup(__xdata void *wchan);
+
+extern alt_t ao_max_height;
+
+extern void ao_report_altitude(void);
+
+void ao_delay_us(uint16_t us);
+
--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+
+volatile AO_TICK_TYPE ao_tick_count;
+static volatile AO_TICK_TYPE ao_wakeup_count;
+
+ISR(TIMER1_COMPA_vect)
+{
+ PORTB ^= 2;
+ ++ao_tick_count;
+ if ((int16_t) (ao_tick_count - ao_wakeup_count) >= 0)
+ ao_wakeup((void *) &ao_tick_count);
+}
+
+uint16_t
+ao_time(void)
+{
+ uint16_t r;
+
+ cli();
+ r = ao_tick_count;
+ sei();
+ return r;
+}
+
+void
+ao_timer_init(void)
+{
+ cli();
+ CLKPR = (1 << CLKPCE);
+ CLKPR = 0;
+ sei();
+
+ /* Overall division ratio is 512 * 125,
+ * so our 8MHz base clock ends up as a 125Hz
+ * clock
+ */
+ TCCR1 = ((1 << CTC1) | /* Clear timer on match */
+ (0 << PWM1A) | /* Not PWM mode */
+ (0 << COM1A0) | /* Don't change output pins */
+ (0 << COM1A1) | /* ... */
+ (1 << CS13) | /* Prescale by 512 */
+ (0 << CS12) | /* ... */
+ (1 << CS11) | /* ... */
+ (0 << CS10)); /* ... */
+ GTCCR = ((0 << PWM1B) | /* Not PWM mode */
+ (0 << COM1B1) | /* Don't change output pins */
+ (0 << COM1B0) | /* ... */
+ (0 << FOC1B) | /* Don't force output compare */
+ (0 << FOC1A) | /* ... */
+ (0 << PSR1)); /* Don't bother to reset scaler */
+
+ OCR1A = 0;
+ OCR1B = 0;
+ OCR1C = 124; /* Divide by as many 5s as we can (5^3 = 125) */
+
+ TIMSK = ((1 << OCIE1A) | /* Enable TIMER1_COMPA interrupt */
+ (0 << OCIE1B) | /* Disable TIMER1_COMPB interrupt */
+ (0 << TOIE1)); /* Disable TIMER1_OVF interrupt */
+ DDRB |= 2;
+}
+
+#define PER_LOOP 8
+#define US_LOOPS ((AVR_CLOCK / 1000000) / PER_LOOP)
+
+void ao_delay_us(uint16_t us)
+{
+#if US_LOOPS > 1
+ us *= US_LOOPS;
+#endif
+ for (;;) {
+ ao_arch_nop();
+ ao_arch_nop();
+ ao_arch_nop();
+ --us;
+ /* A bit funky to keep the optimizer
+ * from short-circuiting the test */
+ if (!((uint8_t) (us | (us >> 8))))
+ break;
+ }
+}
+
+void
+ao_delay_until(uint16_t target)
+{
+ cli();
+ ao_wakeup_count = target;
+ while ((int16_t) (target - ao_tick_count) > 0)
+ ao_sleep((void *) &ao_tick_count);
+ sei();
+}
+
+void
+ao_delay(uint16_t ticks)
+{
+ ao_delay_until(ao_time() + ticks);
+}
+
--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+
+static void
+ao_eeprom_wait(void)
+{
+ /* Wait for previous write to complete */
+ while (EECR & (1 << EEPE))
+ ;
+}
+
+static uint8_t
+ao_eeprom_read_byte(uint16_t addr)
+{
+ uint8_t v;
+
+ ao_eeprom_wait();
+ EEAR = addr;
+ cli();
+ EECR |= (1 << EERE);
+ v = EEDR;
+ sei();
+ return v;
+}
+
+static void
+ao_eeprom_write_byte(uint16_t addr, uint8_t v)
+{
+ ao_eeprom_wait();
+ EECR = (0 << EEPM1) | (0 << EEPM0);
+ EEAR = addr;
+ EEDR = v;
+ cli();
+ EECR |= (1 << EEMPE);
+ EECR |= (1 << EEPE);
+ sei();
+}
+
+void
+ao_eeprom_read(uint16_t addr, void *buf, uint16_t len)
+{
+ uint8_t *b = buf;
+
+ while (len--)
+ *b++ = ao_eeprom_read_byte(addr++);
+}
+
+void
+ao_eeprom_write(uint16_t addr, void *buf, uint16_t len)
+{
+ uint8_t *b = buf;
+
+ while (len--)
+ ao_eeprom_write_byte(addr++, *b++);
+}
--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+#include <ao_exti.h>
+
+static void (*pcint_callback)(void);
+static uint8_t pcint_mask;
+
+ISR(PCINT0_vect)
+{
+ if (PINB & pcint_mask)
+ (*pcint_callback)();
+}
+
+void
+ao_exti_setup_port(uint8_t pin, uint8_t mode, void (*callback)(void))
+{
+ pcint_callback = callback;
+ pcint_mask = (1 << pin);
+ ao_exti_disable(PORTB, pin);
+ GIMSK |= (1 << PCIE);
+}
--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#ifndef _AO_EXTI_H_
+#define _AO_EXTI_H_
+
+void
+ao_exti_setup_port(uint8_t pin, uint8_t mode, void (*callback)(void));
+
+#define ao_exti_setup(port, pin, mode, callback) ao_exti_setup_port(pin, mode, callback)
+
+#define ao_exti_enable(gpio, pin) (PCMSK |= (1 << (pin)))
+
+#define ao_exti_disable(gpio, pin) (PCMSK &= ~(1 << (pin)))
+
+#define ao_exti_init()
+
+#define AO_EXTI_MODE_RISING 1
+
+#endif /* _AO_EXTI_H_ */
--- /dev/null
+/*
+ * Copyright © 2011 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+
+/*
+ * ATtiny USI as an I2C interface
+ */
+
+#define I2C_USICR ((0 << USISIE) | /* No start condition interrupt */ \
+ (0 << USIOIE) | /* No counter overflow interrupt */ \
+ (1 << USIWM1) | /* Two-wire mode */ \
+ (0 << USIWM0) | /* ... */ \
+ (1 << USICS1) | /* Software clock strobe */ \
+ (0 << USICS0) | /* ... */ \
+ (1 << USICLK)) /* ... */ \
+
+#define I2C_USICR_TICK (I2C_USICR | (1 << USITC)) /* Toggle the clock on every write */
+
+#define I2C_USISR_1BIT ((1<<USISIF)| /* Clear start condition flag */ \
+ (1<<USIOIF)| /* Clear overflow flag */ \
+ (1<<USIPF)| /* Clear stop condition flag */ \
+ (1<<USIDC)| /* Clear data collision flag */ \
+ (0xE<<USICNT0)) /* Set counter value to 0xe */
+
+#define I2C_USISR_8BIT ((1<<USISIF)| /* Clear start condition flag */ \
+ (1<<USIOIF)| /* Clear overflow flag */ \
+ (1<<USIPF)| /* Clear stop condition flag */ \
+ (1<<USIDC)| /* Clear data collision flag */ \
+ (0x0<<USICNT0)) /* Set counter value to 0 */
+
+#define T2_TWI 5 /* >4.7μs */
+#define T4_TWI 4 /* >4.0μs */
+
+static inline void ao_i2c_transfer(uint8_t sr)
+{
+ USISR = sr;
+ for (;;) {
+ ao_delay_us(T2_TWI);
+
+ /* Clock high */
+ USICR = I2C_USICR_TICK;
+
+ /* Wait for clock high (clock stretching) */
+ ao_delay_us(T4_TWI);
+ while(!(I2C_PIN & (1<<I2C_PIN_SCL)))
+ ;
+
+ /* Clock low */
+ USICR = I2C_USICR_TICK;
+
+ /* Check for transfer complete */
+ if (USISR & (1 << USIOIF))
+ break;
+ }
+ ao_delay_us(T2_TWI);
+}
+
+static inline uint8_t ao_i2c_get_byte(uint8_t sr)
+{
+ uint8_t ret;
+
+ /* Set SDA to input */
+ I2C_DIR &= ~(1<<I2C_PIN_SDA);
+
+ ao_i2c_transfer(sr);
+
+ ret = USIDR;
+ USIDR = 0xff;
+
+ /* Set SDA to output */
+ I2C_DIR |= (1<<I2C_PIN_SDA);
+
+ return ret;
+}
+
+static uint8_t
+ao_i2c_write_byte(uint8_t byte)
+{
+ /* Pull SCL low */
+ I2C_PORT &= ~(1<<I2C_PIN_SCL);
+
+ /* Write the byte */
+ USIDR = byte;
+
+ /* Clock and verify (N)ACK from slave */
+
+ ao_i2c_transfer(I2C_USISR_8BIT);
+
+ if (ao_i2c_get_byte(I2C_USISR_1BIT) & 0x80)
+ return 0;
+
+ return 1;
+}
+
+static uint8_t
+ao_i2c_read_byte(uint8_t ack)
+{
+ uint8_t ret;
+
+ /* Read the data */
+ ret = ao_i2c_get_byte(I2C_USISR_8BIT);
+
+ /* Ack it */
+ USIDR = ack;
+ ao_i2c_transfer(I2C_USISR_8BIT);
+
+ return ret;
+}
+
+uint8_t
+ao_i2c_start_bus(uint8_t address)
+{
+ /* Release SCL to ensure that (repeated) Start can be performed */
+
+ I2C_PORT |= (1<<I2C_PIN_SCL);
+
+ while( !(I2C_PORT & (1<<I2C_PIN_SCL)) )
+ ;
+ ao_delay_us(T2_TWI);
+
+ /* Generate Start Condition */
+
+ /* Pull SDA low */
+ I2C_PORT &= ~(1<<I2C_PIN_SDA);
+ ao_delay_us(T4_TWI);
+
+ /* Pull SCL low */
+ I2C_PORT &= ~(1<<I2C_PIN_SCL);
+
+ /* Raise SDA */
+ I2C_PORT |= (1<<I2C_PIN_SDA);
+
+ return ao_i2c_write_byte(address);
+}
+
+static void
+ao_i2c_stop_bus(void)
+{
+ /* Pull SDA low. */
+ I2C_PORT &= ~(1<<I2C_PIN_SDA);
+
+ /* Release SCL. */
+ I2C_PORT |= (1<<I2C_PIN_SCL);
+
+ /* Wait for SCL to go high */
+ while( !(I2C_PIN & (1<<I2C_PIN_SCL)) );
+ ao_delay_us(T4_TWI);
+
+ /* Raise SDA */
+ I2C_PORT |= (1<<I2C_PIN_SDA);
+ ao_delay_us(T2_TWI);
+}
+
+/* Send bytes over SPI.
+ *
+ * This just polls; the SPI is set to go as fast as possible,
+ * so using interrupts would take way too long
+ */
+uint8_t
+ao_i2c_send_bus(void __xdata *block, uint16_t len, uint8_t stop)
+{
+ uint8_t *d = block;
+
+ while (len--)
+ if (!ao_i2c_write_byte (*d++))
+ return 0;
+ if (stop)
+ ao_i2c_stop_bus();
+ return 1;
+}
+
+/* Send bytes over SPI.
+ *
+ * This just polls; the SPI is set to go as fast as possible,
+ * so using interrupts would take way too long
+ */
+uint8_t
+ao_i2c_send_fixed_bus(uint8_t d, uint16_t len, uint8_t stop)
+{
+ while (len--)
+ if (!ao_i2c_write_byte (d))
+ return 0;
+ if (stop)
+ ao_i2c_stop_bus();
+ return 1;
+}
+
+/* Receive bytes over SPI.
+ *
+ * Poll, sending zeros and reading data back
+ */
+uint8_t
+ao_i2c_recv_bus(void __xdata *block, uint16_t len, uint8_t stop)
+{
+ uint8_t *d = block;
+
+ while (len--)
+ *d++ = ao_i2c_read_byte (len ? 0x00 : 0xff);
+ if (stop)
+ ao_i2c_stop_bus();
+ return 1;
+}
+
+/*
+ * Initialize USI
+ *
+ * Chip select is the responsibility of the caller
+ */
+
+void
+ao_i2c_init(void)
+{
+ /* Pull-ups on SDA and SCL */
+ I2C_PORT |= (1<<I2C_PIN_SDA);
+ I2C_PORT |= (1<<I2C_PIN_SCL);
+
+ /* SCL and SDA are outputs */
+ I2C_DIR |= (1<<I2C_PIN_SCL);
+ I2C_DIR |= (1<<I2C_PIN_SDA);
+
+ USIDR = 0xFF;
+ USICR = I2C_USICR;
+}
--- /dev/null
+/*
+ * Copyright © 2009 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao.h"
+
+__pdata uint8_t ao_led_enable;
+
+#define LED_PORT PORTB
+#define LED_DDR DDRB
+
+void
+ao_led_on(uint8_t colors)
+{
+ LED_PORT |= (colors & ao_led_enable);
+}
+
+void
+ao_led_off(uint8_t colors)
+{
+ LED_PORT &= ~(colors & ao_led_enable);
+}
+
+void
+ao_led_set(uint8_t colors)
+{
+ LED_PORT = (LED_PORT & ~(ao_led_enable)) | (colors & ao_led_enable);
+}
+
+void
+ao_led_toggle(uint8_t colors)
+{
+ LED_PORT ^= (colors & ao_led_enable);
+}
+
+void
+ao_led_for(uint8_t colors, uint16_t ticks) __reentrant
+{
+ ao_led_on(colors);
+ ao_delay(ticks);
+ ao_led_off(colors);
+}
+
+void
+ao_led_init(uint8_t enable)
+{
+ ao_led_enable = enable;
+ LED_PORT &= ~enable;
+ LED_DDR |= enable;
+}
--- /dev/null
+/*
+ * Copyright © 2011 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+
+/*
+ * ATtiny USI as a SPI interface
+ */
+
+/*
+ * Transfer one byte in/out of the USI interface
+ */
+
+/* Three wire mode */
+#define SPI_USICR_WM ((0 << USIWM1) | (1 << USIWM0))
+#define SPI_USICR_CS ((1 << USICS1) | (0 << USICS0) | (1 << USICLK))
+
+#define SPI_USICR_FAST_2 ((1 << USIWM0) | (1 << USITC))
+#define SPI_USICR_FAST_1 ((1 << USIWM0) | (1 << USITC) | (1 << USICLK))
+
+
+static uint8_t
+ao_spi_transfer(uint8_t i)
+{
+ /* Load data register */
+ USIDR = i;
+
+#if 1
+ USISR = (1 << USIOIF);
+ do {
+ USICR = SPI_USICR_WM | SPI_USICR_CS | (1 << USITC);
+ } while ((USISR & (1 << USIOIF)) == 0);
+#else
+ /* 8 clocks */
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+
+ USICR = SPI_USICR_FAST_1;
+ USICR = SPI_USICR_FAST_2;
+#endif
+
+ /* Pull data from the port */
+ return USIDR;
+}
+
+/* Send bytes over SPI.
+ *
+ * This just polls; the SPI is set to go as fast as possible,
+ * so using interrupts would take way too long
+ */
+void
+ao_spi_send_bus(void __xdata *block, uint16_t len) __reentrant
+{
+ uint8_t *d = block;
+
+ while (len--)
+ ao_spi_transfer (*d++);
+}
+
+/* Receive bytes over SPI.
+ *
+ * Poll, sending zeros and reading data back
+ */
+void
+ao_spi_recv_bus(void __xdata *block, uint16_t len) __reentrant
+{
+ uint8_t *d = block;
+
+ while (len--)
+ *d++ = ao_spi_transfer (0xff);
+}
+
+/*
+ * Initialize USI
+ *
+ * Chip select is the responsibility of the caller
+ */
+
+void
+ao_spi_init(void)
+{
+#if 1
+ USICR = (1 << USIWM0) | (1 << USICS1) | (1 << USICLK);
+#else
+ USICR = SPI_USICR_FAST_2;
+#endif
+ SPI_DIR &= ~(1 << DDB0); /* DI */
+ SPI_DIR |= (1 << DDB1); /* DO */
+ SPI_DIR |= (1 << DDB2); /* SCLK */
+ SPI_DIR |= (1 << DDB3); /* CS */
+}
projects / fw / altos / commitdiff