LuatOS IO multiplexing configuration under firmware#

This document describes the LuatOS perspective

  1. Due to the existence of firmware characteristics, LuatOS’s io multiplexing is fixed by default. Starting from V1107, the mapping can be partially modified through mcu.iomux function.

  2. The external pin layout of different modules is different, but the’ PAD(paddr)’value is the same. to correspond to the “PIN/GPIO correspondence table” document, the document can be found in air780e.cn

  3. Due to the small number of pins in the chip, there are a large number of multiplexing scenarios, and many functions will conflict.

  4. For AT firmware, this document is meaningless, please ignore it.

  5. For CSDK, relevant reuse can be modified, so please ignore this document

  6. Air600E Doomed not suitable for secondary development, some pins in the hardware design manual description will be different, pay attention to distinguish

  7. Cloud compilation and mcu.iomux function can adjust part of the reuse relationship, please refer to the document linked to mcu library

  8. If SIM2 is used, it will take up 4 IO(gpio4/5/6/23)

PWM Description#

The actual available channels are 4 (0/1/2/4), but each has 3 configurations, PWM3/PWM5 has been used by the bottom layer.

For example, PWM1 and PWM11 both use hardware channel 1, only one of them can be selected to use.

PWM11 cannot be enabled when PWM1 is enabled. when calling the API of pwm library, fill in software channel id

software channel id

actual hardware channel

corresponding GPIO

corresponding PAD

remarks

0

0

GPIO23

43

AGPIO3,Weak drive capability. Avoid using this pin

1

1

GPIO24

44

MAIN_RI,Actually AGPIO4, weak driving ability

2

2

GPIO25

45

AGPIO5,weak driving ability

4

4

GPIO27

47

NetLed,Network Status Light

10

0

GPIO1

16

LCD_RST,Actual is normal GPIO

11

1

GPIO2

17

MAIN_DCD,Actual is normal GPIO

12

2

GPIO16

31

MAIN_CTS,Actual is normal GPIO

14

4

GPIO18

33

UART1_RXD/MAIN_RXD

20

0

None

39

I2S_MCLK

21

1

GPIO29

35

I2S_BCLK

22

2

GPIO30

36

I2S_LRCK

PS:

  1. Software channel 10/11/12/14 requires firmware above V1002, 20221219 later compiled version

  2. Software channels 20/21/22 require firmware above V1016, 20230330 later compiled versions

  3. The above mapping is fixed, mcu.iomux has no configuration items, and all available PWM channels have been enumerated..

UART Description#

physical uart has 3(0/1/2)

  1. uart0 It is a log port (DBG_TX/DBG_RX), which is not recommend to use and has output during startup. LuatOS firmware does not allow users to use it by default uart0

  2. uart1 is the primary serial port (MAIN_TX/MAIN_RX), recommend use

  3. uart2 This is a serial port (AUX_TX/AUX_RX), the module with GNSS function will be connected to the GNSS chip, and the PAD is different and cannot be used for other functions

  4. Note that UART2 is different from Air780EG PAD in Air780E, but the software will automatically adapt and does not need attention.

  5. The following mappings are default, configurable via mcu.iomux

  6. Cloud Compilation supports releasing uart0, although this is not recommend..

Function

Software Meaning

Corresponding GPIO

Corresponding PAD

Remarks

DBG_RX

UART0_RX

-

29

DBG_TX

UART0_TX

-

30

MAIN_RX

UART1_RX

GPIO18

33

MAIN_TX

UART1_TX

GPIO19

34

AUX_RX

UART2_RX

GPIO10

25

Air780EG In PAD 27

AUX_TX

UART2_TX

GPIO11

26

Air780EG In PAD 28

I2C Description#

  1. Physics i2c has 2(0/1)

  2. The following mappings are default, configurable via mcu.iomux

  3. Air780EX Only I2C0, and need to call’ mcu.iomux(mcu.I2C, 0,2) ‘to switch to PAD 31/32 GPIO 16/17

Function

Software Meaning

Corresponding GPIO

Corresponding PAD

Remarks

I2C0_SCL

I2C0 Clock

GPIO14

13

GPIO function see description later

I2C0_SDA

I2C0 Data

GPIO15

14

GPIO functions see description later

I2C1_SCL

I2C1 Clock

GPIO9

24

conflicts with SPI0

I2C1_SDA

I2C1 Data

GPIO8

23

Conflicts with SPI0

SPI Description#

  1. Physical SPI has 2(0/1)

  2. The following mappings are default, configurable via mcu.iomux

Function

Software Meaning

Corresponding GPIO

Corresponding PAD

Remarks

SPI0_CS

SPI0 Chip Select

GPIO8

23

Conflicts with I2C1

SPI0_MOSI

SPI0 Host output

GPIO9

24

conflicts with I2C1

SPI0_MISO

SPI0 Output from machine

GPIO10

25

SPI0_SCL

SPI0 Clock

GPIO11

26

SPI1_CS

SPI1 Film selection

GPIO12

27

SPI1_MOSI

SPI1 Host Output

GPIO13

28

SPI1_MISO

SPI1 slave output

-

29

note no GPIO function

SPI1_SCL

SPI1 Clock

-

30

Note no GPIO capability

Attention:

  1. SPI0 It is in conflict with UART2/I2C1, which is the case.

  2. SPI1 Although MISO and SCL can be reused as GPIO14/15, these GPIO are actually mapped to other pins. see GPIO additional instructions

GPIO Additional Instructions#

  1. GPIO14/15 There are changes in V1103, correctly mapped PAD 13/14

  2. Ordinary GPIO in deep sleep/SLEEP2, there will be periodic high-level pulses, be sure to pay attention

  3. AONGPIO It is a GPIO that can still maintain a high level during sleep, but the driving ability is very weak.

  4. GPIO12/GPIO13 There are two types of mapping, using different APIs.

  5. When ordinary GPIO is configured in input/interrupt mode, the up-down pull cannot be set. If the default up-down pull cannot meet the requirements, it can be set to’0’ to cancel the default up-down pull, and then add the pull-down externally

  6. GPIO20,21,22 When configured to interrupt mode, it is a wakeup function, which can be configured to pull up and down or cancel the use of external pull up and down.

  7. GPIO23 After power-on, the input pull-down is first, and then it will be set to output pull-up high level. It is recommended to avoid using this GPIO

  8. **Note **, only GPIO 20-22 supports ‘two-way triggering (rising and falling) ‘, other GPIOs only support one-way triggering of ‘rising edges’ or ‘falling edges’

  9. GPIO 20-25 The level flip speed of is slower than other GPIO

  10. When using GPIO with multiplexing function, the default GPIO pin needs to be multiplexed into other functions before multiplexing can be used normally.GPIO

    -- Using the 97-pin GPIO12, the 58-pin GPIO12 needs to be multiplexed into I2C or UART function first.
-- Multiplexing pins 57 and 58 I2C0
mcu.iomux(mcu.I2C, 0, 1)
-- Enable I2C
i2c.setup(0, i2c.SLOW)

local function gpio12CbFnc()
	log.info("gpio", "12")    
end

-- Enable multiplexing for ALT4, pin 97 GPIO12
gpio.setup(12, gpio12CbFnc, gpio.PULLUP, gpio.FALLING, 4)

Corresponding GPIO

Corresponding PAD

Examples of API used

Remarks

GPIO12

11

pm.power(pm.DAC_EN, true Or false)

LDO_CTL, the Air600E target is GPIO12

GPIO13

12

pm.power(pm.GPS, true Or false)

no lead, in the Air780EG to control the power of GPS

GPIO12

27

gpio.setup(12, 0)

I2C0_SDA,is also multiplexed

GPIO13

28

gpio.setup(13, 0)

I2C0_SCL,is also multiplexed

Virtual GPIO#

Air780E(EC618 The whole system) supports multiple virtual GPIO, and non-GPIO pins are used by software simulation into GPIO.

Number

Name

Function

Remarks

32

wakeup0

Only supports input and interrupt

wakeup0 sleep wake-up pin

33

vbus/wakeup1

Only supports input and interrupt

VBUS of USB, detects whether USB is inserted

34

wakeup2

Only supports input and interrupt

wakeup2 sleep wake-up pin, USIM_DET

35

pwrkey

Only supports input and interrupt

instant power-on key, when normal GPIO is used after power-on

vbus Description:

  1. In CSDK/LuatOS firmware, vbus and USB functions are decoupled

  2. Different from regular understanding, USB function is still available without vbus

  3. Before entering sleep, set the above wakeup0/wakeup1/wakeup2 to interrupt state to realize pin wake-up function

  4. Non-wakeup ordinary GPIO does not support sleep wake-up

For example, if wakup0 is set as the wake-up pin, the interrupt callback can be an empty function.

gpio.setup(32, function() end, gpio.PULLUP)

pwrkey Description:

  1. pwrkey Is the pull-up input, pull-down immediately boot or 1.5 seconds boot, depending on the boot anti-shake enabled(pm.power(pm.PWK_MODE, true))

  2. AT Firmware is the default boot anti-shake, so the corresponding is to pull down 1.5 seconds boot

  3. Corresponding to LuatOS/CSDK firmware, the function of this pin is customized after startup, and it will not shut down after pulling down again. You can shut down through the following code

-- Long press 2 seconds after the shutdown
gpio.debounce(35, 2000, 1)
gpio.setup(35, function()
    log.info("Perform Shutdown")
    pm.shutdown()
end, gpio.PULLUP)

Additional Notes on USB#

  1. **BOOT Mode requires high USB wiring * *, must do differential line and impedance matching!!!

  2. When there is USB communication, it is impossible to sleep. USB communication can be turned off by pass’ pm.power(pm.USB, false)’

  3. UART1 Can also brush the machine, but need to use the amount of production tool brush, LuaTools temporarily does not support the Air780EP/Air780EPV brush through UART!!!