There are several connectors available. On the Pine64 POT Development board, each of the ports for PI-2-Bus, Euler, and Expansion have been given a mnemonic labeling letter (P, E, and X), and although they are identified as J47 etc in the schematics, I will include these letters in the listings and discussions below as needed. I extended this scheme to the Wifi, Bluetooth, and TP ports also.
Pin numbers legend.
| P | PI-2-BUS | (40) |
| E | Euler Bus | (34) |
| X | Expansion Connector | (10) |
| W | Wifi | (14) |
| B | Bluetooth | (16) |
| T | TP connector | (6) |
The (E) marking on some of the GPIO lines means that this gpio-line has support for interrupts. Sysfs will provide an edge file for them.
| P1 3.3V | P2 5.0V |
| P3 PH3 G227 (E) TWI1_SDA | P4 5.0V |
| P5 PH2 G226 (E) TWI1_SCL | P6 Gnd |
| P7 PL10 G362 (E) S_PWM | P8 PB0 G32 (E) UART2_TX |
| P9 Gnd | P10 PB1 G33 (E) UART2_RX |
| P11 PC7 G71 | P12 PC8 G72 1w |
| P13 PH9 G233 (E) | P14 Gnd |
| P15 PC12 G76 | P16 PC13 G77 |
| P17 3.3V | P18 PC14 G78 |
| P19 PC0 G64 SPI0_MOSI | P20 Gnd |
| P21 PC1 G65 SPI0_MISO | P22 PC15 G79 |
| P23 PC2 G66 SPI0_CLK | P24 PC3 G67 SPI0_CS |
| P25 Gnd | P26 PH7 G231 (E) SPK Note 1 |
| P27 PL9 G361 (E) S_TWI_SDA | P28 PL8 G360 (E) S_TWI_SCK |
| P29 PH5 G229 (E) UART3_RX | P30 GND |
| P31 PH6 G230 (E) UART3_RTS | P32 PC4 G68 |
| P33 PC5 G69 | P34 GND |
| P35 PC9 G73 | P36 PC6 G70 |
| P37 PC16 G80 | P38 PC10 G74 |
| P39 Gnd | P40 PC11 G75 |
There are spaces on the board for pull-up resistors on TWI1_SDA R9705 and TWI1_SCL R9706 (page 17) but none have been fitted. Schematics indicate these should be 2 kΩ. These resistors are tiny surface-mount ones, R0402 form factor.
| E1 3.3V | E2 DC IN |
| E3 Lithium Batt+ | E4 DC IN |
| E5 Temp Sensor | E6 Gnd |
| E7 PL11 G363 (E) IR_RX | E8 5 V |
| E9 Gnd | E10 PH8 G232 (E) SPDIF OWA_OUT |
| E11 PB3 G35 (E) UART2_CTS I2S_MCK | E12 PB4 G36 (E) I2S_SYNC |
| E13 PB5 G37 (E) I2S_BCK | E14 Gnd |
| E15 PB6 G38 (E) I2S_DOUT | E16 PB7 G39 (E) I2S_DIN |
| E17 3.3V | E18 PD4 G100 UART4_RTS |
| E19 PD2 G98 UART4_TX SPI1_MOSI | E20 Gnd |
| E21 PD3 G99 UART4_RX SPI1_MISO | E22 PD5 G101 UART4_CTS |
| E23 PD1 G97 UART3_RX SPI1_SCK | E24 PD0 G96 UART3_TX SPI1_CS |
| E25 Gnd | E26 PD6 G102 |
| E27 PB2 G34 (E) UART2_RTS | E28 PD7 G103 |
| E29 PB8 G40 (E) UART0_TX | E30 PB9 G41 (E) UART0_RX |
| E31 EAROUTP | E32 EAROUTN |
| E33 NC | E34 GND |
The unit can be powered via the micro-usb connector, or with 5V applied to pins E2 and E4, 0V on any or all of the pins E6, E9, E14, E20, E25, E34.
| X1 3.3V | X2 PL7 G359 (E) System LED -K |
| X3 Charger LED -K | X4 Reset Sw |
| X5 Pwr Stb Sw | X6 Gnd |
| X7 PB8 G40 (E) UART0_TX | X8 PB9 G41 (E) UART0_RX (G) |
| X9 Gnd | X10 KeyADC |
Pins X2 and X3 are also connected to the Cathode, or negative, side of the Charger LED and System LED. The positive side of these LEDs should be returned to +3.3V via a resistor, in the usual way. The pins here do not include any such resistors, while the connection points on the edge of the board do: (schematics v2 page 12), where the one for the Charge LED is 1kΩ and the one for the System LED, PL7, is 510Ω. Similarly sized resistors will be needed in series with LEDs connected here at pins X2 and X3.
Pins X4 and X5 are switch inputs, the other side of these switches should go to 0V. The necessary 1kΩ pull-up resistors are already in place.
Pins X8 connects to the UART0 RX line (PB9) via a MOSFET, so when power is off, any High voltage impressed on the RX line (X8) doesn't try to backfeed power into the Pine. This is in contrast to the connection to the UART0 on pin E30 where no such protection exists. Thus, when connecting to another device for looking at the bootup messages on the serial port, these pins, X7 and X8, are the ones that should be used.
| W1 GND | W2 PG2 G194 (E)SDC1-D0 SDIO-D0 |
| W3 PG0 G192 (E) SDC1-CK SDIO-CLK | W4 PG3 G195 (E) SDC1-D1 SDIO-D1 |
| W5 GND | W6 PG4 G196 (E) SDC1-D2 SDIO-D2 |
| W7 PG1 G193 (E) SDC1-CMD SDIO-CMD | W8 PG5 G197 (E) SDC1-D3 SDIO-D3 |
| W9 PL2 G354 (E) S-UART-TX WL-REG-ON | W10 X32KFOUT AP-CK32KO |
| W11 PL3 G355 (E) S-UART-RX WL-WAKE-AP | W12 GND |
| W13 VCC-WIFI (3.3V) | W14 VCC-WIFI (3.3V) |
| B1 PG10 G202 (E) AIF3-SYNC PCB1-SYNC BT-PCM-SYNC | B2 PG6 G198 (E) UART1-TX BT-UART-RX |
| B3 PG11 G203 (E) AIF3-CLK PCB1-BCLK BT-PCM-BCLK | B4 PG7 G199 (E) UART1-RX BT-UART-TX |
| B5 PG12 G204 (E) AIF3-DOUT PCB1-DOUT BT-PCM-DIN | B6 PG8 G200 (E) UART1-RTS BT-UART-CTS |
| B7 PG13 G205 (E) AIF3-DIN PCB1-DIN BT-PCM-DOUT | B8 PG9 G201 (E) UART1-CTS BT-UART-RTS |
| B9 GND | B10 GND |
| B11 PL5 G357 (E) S-JTAG-CK BT-WAKE-AP | B12 PL4 G356 (E) S-JTAG-MS BT-RST-N |
| B13 PL6 G358 (E) S-JTAG-DO AP-WAKE-BT | B14 VCC-WIFI-IO (1.8V) |
| B15 GND | B16 GND |
This is the connector for the touch-sensor on the LCD. When the LCD is not being used, there is a functional i2c bus (/dev/i2c-0) and two more GPIO lines available here. The standard connection is via a narrow flat cable, but there are pads on the underside of the board that provide points to which wires can be soldered. Schematics indicate that this i2c-bus has the necessary pull-up resistors fitted, but this needs to be verified.
| T1 PH11 G235 (E) CTP_RST | TP23 |
| T2 PH4 G228 (E) CTP_INT UART3_TX | TP24 |
| T3 PH0 G224 (E) TWI0_SCL | TP25 |
| T4 PH1 G225 (E) TWI0_SDA | TP26 |
| T5 VCC-CTP (3.3V) | TP28 |
| T6 Gnd | TP27 |
Under the TP connector on the top of the card, there are 6 test-points in a 3 by 2 staggered formation, which are TP23 thru TP28, counting from the nearest corner of the card (near the HDMI). The first four of these are T1 thru T4 in that order, the next one is T6 GND and the last one is T5 VCC-CTP, which appears to be open, since the channel named GPIO0LDO from the power distribution chip has this turned off. We can backfeed +3.3V in here to bias the SDA and SCL or use a kernel-module that contain the necessary calls to turn the power on.
There is a bunch of sysfs references to this and the other channels in /sys/devices/platform, notably /sys/devices/platform/reg-81x-cs-gpio0ld0/
G T3 T1 T5 T4 T2
Power-control is using an internal TWI bus, via PL1/PL0 which are configured to mode 2, S_RSB_SDA/S_RSB_SCL. Maybe the upower daemon can talk with this?
In sysfs there is also the file which identifies as name being the gpio0ldo, and it has state disabled, indicating it is turned off. Other regulator-files are present for the other channels out of the power chip.
/sys/devices/platform/axp81x_board/axp-regulator.30/regulator/regulator.21/name /sys/devices/platform/axp81x_board/axp-regulator.30/regulator/regulator.21/state
See the pages on on i2c and on kernel hacking for notes on how to turn the power on this regulator on and off.
The Camera, CSI, and Display, DSI ports might possibly also be re-purposed, where at least some GPIOs may be available. Schematics indicates that CSI is hooked up to ports in the PE range, and the DSI has ports in the PD range. These are all 2.5 V Vio and none of them support interrupts, so this seems to put them rather far down in priority for further re-use, considering the tedium of connecting the 40 or so tiny wires.
