![\"rpi_io_pinouts\"](\"https:\/\/raspberry-projects.com\/pi\/wp-content\/uploads\/2012\/04\/rpi_io_pinouts1.jpg\")
<\/a>\n<\/h4>\n
\n3.3V Output
\n<\/h4>\n
\nExternal circuitry may draw up to a total of 50mA max current from the 3.3V Out pins.\n<\/p>\n
\nIs maximum current from 3.3V pin really 50mA?<\/a>\n<\/p>\n \nAll IO pins are 3.3V, not 1.8V. Pins are not 5V tolerant.\n<\/p>\n \nFull details are available here<\/a>\n<\/p>\n \nMaximum 16mA per IO pin with the total current from all pins not exceeding 51mA. See a detailed explanation here<\/a>.\n<\/p>\n \nIts likely all pins are set as inputs on power up (TBC).\n<\/p>\n \nI2C pins (e.g. P1-3 and P1-5) are therefore high due to the pull up resistors on these pins.\n<\/p>\n \n1K8 pull up resistors are included on the RPi board so are not needed externally. When enabling the I2C port it seems both ports are enabled – is it possible to only enable 1 port and use the other I2C port as IO pins? Our assumption in Raspbian is no but we've not had reason to try and achieve this.\n<\/p>\n \nInterfacing the RPi 3.3V I2C pins to a 5V device like an Arduino – see here<\/a>.\n<\/p>\n \nThe Chip Select signals are for up to two independent slave devices. It seems that with the SPI port enabled in Raspbian both the CS0 and CS1 pins are assigned to it and therefore can't be used as IO (our assumption – correct?)\n<\/p>\n \nThe PWM pin available on the GPIO header is shared with the Audio system. This means that you can't use the PWM output and play audio through the 3.5mm jack at the same time.\n<\/p>\n\nIO Pins
\n<\/h4>\n\nMax Current
\n<\/h5>\n\nPower-up State
\n<\/h5>\n\nI2C
\n<\/h4>\n\nSPI
\n<\/h4>\n\nPWM Pin
\n<\/h4>\n\n3.3V \/ 5V Interfacing
\n<\/h4>\n