odroid U3 / shield
Ein Nachbau des ODROID U3 IO Shield mit folgenden Funktionen:
AVR ATMega 1284p
20MHz
2x USART, davon einer am U3
3.3V I2C Pegelwandler für U3
5V I2C Pegelwandler für U3
RTC PCF8515
USART-Bootloader
3 LEDs
Pinleisten für USART, I2C, PWM, IOs, 3.3V, 5V
3.3V DC/DC Regler
5V DC/DC Regler für Versorgung des U3
| PA0 (ADC0/PCINT0) | | | |
| PA1 (ADC1/PCINT1) | | | |
| PA2 (ADC2/PCINT2) | | | |
| PA3 (ADC3/PCINT3) | | | |
| PA4 (ADC4/PCINT4) | | | |
| PA5 (ADC5/PCINT5) | | | |
| PA6 (ADC6/PCINT6) | | | |
| PA7 (ADC7/PCINT7) | | | |
| GND | +5V | +3V3 | PC5 (TDI/PCINT21) |
| GND | +5V | +3V3 | PC4 (TDO/PCINT20) |
| GND | +5V | +3V3 | PC3 (TMS/PCINT19) |
| GND | +5V | +3V3 | PC2 (TCK/PCINT18) |
| GND | OC0A (PB3/PCINT11/OC0A/AIN1) |
| GND | OC0B (PB4/PCINT12/OC0B/!SS) |
| GND | OC1A (PD5/PCINT29/OC1A) |
| GND | OC1B (PD4/PCINT28/XCK1/OC1B) |
| GND | OC2A (PD7/OC2A/PCINT31) |
| GND | OC2B (PD6/PCINT30/OC2B/ICP) |
| GND | TOSC1 (PC6/TOSC1/PCINT22) |
| GND | TOSC2 (PC7/TOSC2/PCINT23) |
| I2C |
| 5V | SCL | SDA | GND |
| 3V3 | SCL | SDA | GND |
| I2C_M1284 |
| 5V | SCL | SDA | GND |
| SIO_M1284 |
| GND | RXD | TXD | 5V |
LEDs
| LED 1 | PB0 (low) |
| LED 2 | PB1 (low) |
| LED 3 | PB2 (low) |
USART
RXD0/TXD0 vom Atmega sind mit /dev/ttySAC0 verbunden.
Bootloader
Der Bootloader startet sofort nach !RESET und ist für ca. 3s aktiv. Um den Bootloader zu aktivieren wird eine spezielle Zeichenkette erwartet, andernfalls startet das Programm an Adresse 0.
#!/usr/bin/env python
import serial
import time
import os.path
import sys
import subprocess
GPIO_NR=204
GPIO_DIR='/sys/class/gpio/gpio%i/'%GPIO_NR
BOOT_ENTER_STR="DEADBEEF"
BOOT_REQUIRED_STR="BOOT.RUN"
SER_DEVICE="/dev/ttySAC0"
BAUDRATE=57600
AVRDUDE_ARGS=[
"avrdude",
"-P", SER_DEVICE,
"-c", "avr109",
"-p", "m1284p",
"-b", "%i"%BAUDRATE
]
if not os.path.isdir(GPIO_DIR):
f=open('/sys/class/gpio/export','w')
f.write('%i\n'%GPIO_NR)
f.flush()
f.close()
def doReset():
reset_gpio=open(GPIO_DIR+'direction','w')
reset_gpio.write("out\n")
reset_gpio.flush()
time.sleep(0.1)
reset_gpio.write("in\n")
reset_gpio.flush()
time.sleep(0.1)
reset_gpio.close()
ser=serial.Serial(SER_DEVICE,baudrate=BAUDRATE)
while True:
print("Searching for bootloader.")
doReset()
boot_response=ser.readline().replace('\x00','').strip()
print('greeting:', boot_response)
ser.write(BOOT_ENTER_STR)
boot_response=ser.readline().replace('\x00','').strip()
print('enter-response:',boot_response)
if boot_response==BOOT_REQUIRED_STR:
break
ser.close()
print("calling AVRDUDE")
subprocess.call(AVRDUDE_ARGS+sys.argv[1:])
/usr/local/bin/exynos_load -U flash:w:/root/ledtest.hex
