Power consumption on UART

[Syl20D]

Hello,

I'm trying to reduce the power conception of my custom board with a nrf52840 and a 4g modem on uart.

For this test, I reduce the code to a loop (modem is off)

        k_msleep(5000);

        pm_device_action_run(modem_uart, PM_DEVICE_ACTION_RESUME);

        k_msleep(5000);

        pm_device_action_run(modem_uart, PM_DEVICE_ACTION_SUSPEND);

 

If I disable the rx to the uart on modem pins with disable-rx; on dts file:

Current is  30µA on suspend, 1.5mA on resume -> this is what I expect but I need RX 

 

If I put the uart on others pins(unconnected) with RX enable:

Current is  30µA on suspend, 1.5mA on resume -> it's OK

 

If I put the uart on the modem pin.

Current is  500µA on suspend, 1.5mA on resume.

 

I assume modem have a ON lvl on its TX even when off and draws current.

But I can't explain why it is not disconnected when the suspend happens. This is the purpose of "low-power-enable": disconnect the pin and put it as a input.

Why I have a difference between disable-rx and low-power-enable options?

 

uart pins in DTS file:

 uart1_default: uart1_default {

         group1 {

             psels = <NRF_PSEL(UART_TX, 1, 7)>,

                        <NRF_PSEL(UART_RX, 1, 4)>;

         };

     };

     

uart1_sleep: uart1_sleep {

        group1 {

            psels = <NRF_PSEL(UART_TX, 1,7)>,<NRF_PSEL (UART_RX, 1,4)>;

            low-power-enable;

        };

    };

 

I tried async uart, with uart_rx_disable before suspend but idle current is now 3mA! I tried the low power uart but current is 500µ too.

How can I have a low current of 30uA  with the suspend mechanism ( or other solution)

Thanks you

[Susheel Nuguru]

Hi Sylvain,

If I put the uart on the modem pin.

Current is  500µA on suspend, 1.5mA on resume.

Which modem pin are you using? Are you sure that P1.04 is not used for anything else?

Can you post me your zephyr.dts file from your build\zephyr  folder?

[Syl20D]

Rx is on Uart Tx of the modem  and TX is on Uart Rx.

I don't understand why disable-rx option has a different power consumption than low-power enable.

Find my zephyr.dts below, thanks

/dts-v1/;

/ {
    #address-cells = < 0x1 >;
    #size-cells = < 0x1 >;
    model = "Custom Plank Board";
    compatible = "vendor,custom-plank";
    chosen {
        zephyr,entropy = &cryptocell;
        zephyr,flash-controller = &flash_controller;
        zephyr,console = &cdc_acm_uart0;
        zephyr,sram = &sram0;
        zephyr,flash = &flash0;
        zephyr,user = &gpio0;
        zephyr,shell-uart = &cdc_acm_uart0;
        zephyr,uart-mcumgr = &cdc_acm_uart0;
        zephyr,code_partition = &slot0_partition;
    };
    aliases {
        pwm-led0 = &pwm_led0;
        modem = &modem;
        gnss = &gnss;
        lte = &lte;
    };
    soc {
        #address-cells = < 0x1 >;
        #size-cells = < 0x1 >;
        compatible = "nordic,nrf52840-qiaa", "nordic,nrf52840", "nordic,nrf52", "simple-bus";
        interrupt-parent = < &nvic >;
        ranges;
        nvic: interrupt-controller@e000e100 {
            #address-cells = < 0x1 >;
            compatible = "arm,v7m-nvic";
            reg = < 0xe000e100 0xc00 >;
            interrupt-controller;
            #interrupt-cells = < 0x2 >;
            arm,num-irq-priority-bits = < 0x3 >;
            phandle = < 0x1 >;
        };
        systick: timer@e000e010 {
            compatible = "arm,armv7m-systick";
            reg = < 0xe000e010 0x10 >;
            status = "disabled";
        };
        ficr: ficr@10000000 {
            compatible = "nordic,nrf-ficr";
            reg = < 0x10000000 0x1000 >;
            #nordic,ficr-cells = < 0x1 >;
            status = "okay";
        };
        uicr: uicr@10001000 {
            compatible = "nordic,nrf-uicr";
            reg = < 0x10001000 0x1000 >;
            status = "disabled";
        };
        sram0: memory@20000000 {
            compatible = "mmio-sram";
            reg = < 0x20000000 0x40000 >;
        };
        clock: clock@40000000 {
            compatible = "nordic,nrf-clock";
            reg = < 0x40000000 0x1000 >;
            interrupts = < 0x0 0x1 >;
            status = "okay";
        };
        power: power@40000000 {
            compatible = "nordic,nrf-power";
            reg = < 0x40000000 0x1000 >;
            interrupts = < 0x0 0x1 >;
            status = "okay";
            #address-cells = < 0x1 >;
            #size-cells = < 0x1 >;
            gpregret1: gpregret1@4000051c {
                #address-cells = < 0x1 >;
                #size-cells = < 0x1 >;
                compatible = "nordic,nrf-gpregret";
                reg = < 0x4000051c 0x1 >;
                status = "okay";
            };
            gpregret2: gpregret2@40000520 {
                #address-cells = < 0x1 >;
                #size-cells = < 0x1 >;
                compatible = "nordic,nrf-gpregret";
                reg = < 0x40000520 0x1 >;
                status = "okay";
            };
        };
        radio: radio@40001000 {
            compatible = "nordic,nrf-radio";
            reg = < 0x40001000 0x1000 >;
            interrupts = < 0x1 0x1 >;
            status = "okay";
            ieee802154-supported;
            ble-2mbps-supported;
            ble-coded-phy-supported;
            tx-high-power-supported;
            ieee802154: ieee802154 {
                compatible = "nordic,nrf-ieee802154";
                status = "disabled";
            };
        };
        uart0: uart@40002000 {
            compatible = "nordic,nrf-uarte";
            reg = < 0x40002000 0x1000 >;
            interrupts = < 0x2 0x1 >;
            status = "disabled";
            disable-rx;
        };
        i2c0: i2c@40003000 {
            compatible = "nordic,nrf-twi";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40003000 0x1000 >;
            clock-frequency = < 0x186a0 >;
            interrupts = < 0x3 0x1 >;
            easydma-maxcnt-bits = < 0x10 >;
            status = "okay";
            pinctrl-0 = < &i2c0_default >;
            pinctrl-1 = < &i2c0_sleep >;
            pinctrl-names = "default", "sleep";
            pca9420_pmic@61 {
                compatible = "zephyr,pca9420_pmic";
                reg = < 0x61 >;
            };
            lsm6ds0_detection@6a {
                compatible = "zephyr,lsm6ds0_detection";
                input-gpios = < &gpio1 0xf 0x0 >;
                reg = < 0x6a >;
            };
        };
        spi0: spi@40003000 {
            compatible = "nordic,nrf-spim";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40003000 0x1000 >;
            interrupts = < 0x3 0x1 >;
            max-frequency = < 0x7a1200 >;
            easydma-maxcnt-bits = < 0x10 >;
            status = "disabled";
        };
        i2c1: i2c@40004000 {
            compatible = "nordic,nrf-twim";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40004000 0x1000 >;
            clock-frequency = < 0x186a0 >;
            interrupts = < 0x4 0x1 >;
            easydma-maxcnt-bits = < 0x10 >;
            status = "disabled";
        };
        spi1: spi@40004000 {
            compatible = "nordic,nrf-spim";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40004000 0x1000 >;
            interrupts = < 0x4 0x1 >;
            max-frequency = < 0x7a1200 >;
            easydma-maxcnt-bits = < 0x10 >;
            status = "disabled";
        };
        nfct: nfct@40005000 {
            compatible = "nordic,nrf-nfct";
            reg = < 0x40005000 0x1000 >;
            interrupts = < 0x5 0x1 >;
            status = "disabled";
        };
        gpiote: gpiote0: gpiote@40006000 {
            compatible = "nordic,nrf-gpiote";
            reg = < 0x40006000 0x1000 >;
            interrupts = < 0x6 0x5 >;
            status = "okay";
            instance = < 0x0 >;
            phandle = < 0xa >;
        };
        adc: adc@40007000 {
            compatible = "nordic,nrf-saadc";
            reg = < 0x40007000 0x1000 >;
            interrupts = < 0x7 0x1 >;
            status = "disabled";
            #io-channel-cells = < 0x1 >;
        };
        timer0: timer@40008000 {
            compatible = "nordic,nrf-timer";
            status = "disabled";
            reg = < 0x40008000 0x1000 >;
            cc-num = < 0x4 >;
            max-bit-width = < 0x20 >;
            interrupts = < 0x8 0x1 >;
            prescaler = < 0x0 >;
        };
        timer1: timer@40009000 {
            compatible = "nordic,nrf-timer";
            status = "disabled";
            reg = < 0x40009000 0x1000 >;
            cc-num = < 0x4 >;
            max-bit-width = < 0x20 >;
            interrupts = < 0x9 0x1 >;
            prescaler = < 0x0 >;
            phandle = < 0xb >;
        };
        timer2: timer@4000a000 {
            compatible = "nordic,nrf-timer";
            status = "disabled";
            reg = < 0x4000a000 0x1000 >;
            cc-num = < 0x4 >;
            max-bit-width = < 0x20 >;
            interrupts = < 0xa 0x1 >;
            prescaler = < 0x0 >;
        };
        rtc0: rtc@4000b000 {
            compatible = "nordic,nrf-rtc";
            reg = < 0x4000b000 0x1000 >;
            cc-num = < 0x3 >;
            interrupts = < 0xb 0x1 >;
            status = "disabled";
            clock-frequency = < 0x8000 >;
            prescaler = < 0x1 >;
        };
        temp: temp@4000c000 {
            compatible = "nordic,nrf-temp";
            reg = < 0x4000c000 0x1000 >;
            interrupts = < 0xc 0x1 >;
            status = "okay";
        };
        rng: random@4000d000 {
            compatible = "nordic,nrf-rng";
            reg = < 0x4000d000 0x1000 >;
            interrupts = < 0xd 0x1 >;
            status = "okay";
        };
        ecb: ecb@4000e000 {
            compatible = "nordic,nrf-ecb";
            reg = < 0x4000e000 0x1000 >;
            interrupts = < 0xe 0x1 >;
            status = "okay";
        };
        ccm: ccm@4000f000 {
            compatible = "nordic,nrf-ccm";
            reg = < 0x4000f000 0x1000 >;
            interrupts = < 0xf 0x1 >;
            length-field-length-8-bits;
            status = "okay";
        };
        wdt: wdt0: watchdog@40010000 {
            compatible = "nordic,nrf-wdt";
            reg = < 0x40010000 0x1000 >;
            interrupts = < 0x10 0x1 >;
            status = "okay";
        };
        rtc1: rtc@40011000 {
            compatible = "nordic,nrf-rtc";
            reg = < 0x40011000 0x1000 >;
            cc-num = < 0x4 >;
            interrupts = < 0x11 0x1 >;
            status = "disabled";
            clock-frequency = < 0x8000 >;
            prescaler = < 0x1 >;
        };
        qdec: qdec0: qdec@40012000 {
            compatible = "nordic,nrf-qdec";
            reg = < 0x40012000 0x1000 >;
            interrupts = < 0x12 0x1 >;
            status = "disabled";
        };
        comp: comparator@40013000 {
            compatible = "nordic,nrf-comp";
            reg = < 0x40013000 0x1000 >;
            interrupts = < 0x13 0x1 >;
            status = "disabled";
            #io-channel-cells = < 0x1 >;
        };
        egu0: swi0: egu@40014000 {
            compatible = "nordic,nrf-egu", "nordic,nrf-swi";
            reg = < 0x40014000 0x1000 >;
            interrupts = < 0x14 0x1 >;
            status = "okay";
        };
        egu1: swi1: egu@40015000 {
            compatible = "nordic,nrf-egu", "nordic,nrf-swi";
            reg = < 0x40015000 0x1000 >;
            interrupts = < 0x15 0x1 >;
            status = "okay";
        };
        egu2: swi2: egu@40016000 {
            compatible = "nordic,nrf-egu", "nordic,nrf-swi";
            reg = < 0x40016000 0x1000 >;
            interrupts = < 0x16 0x1 >;
            status = "okay";
        };
        egu3: swi3: egu@40017000 {
            compatible = "nordic,nrf-egu", "nordic,nrf-swi";
            reg = < 0x40017000 0x1000 >;
            interrupts = < 0x17 0x1 >;
            status = "okay";
        };
        egu4: swi4: egu@40018000 {
            compatible = "nordic,nrf-egu", "nordic,nrf-swi";
            reg = < 0x40018000 0x1000 >;
            interrupts = < 0x18 0x1 >;
            status = "okay";
        };
        egu5: swi5: egu@40019000 {
            compatible = "nordic,nrf-egu", "nordic,nrf-swi";
            reg = < 0x40019000 0x1000 >;
            interrupts = < 0x19 0x1 >;
            status = "okay";
        };
        timer3: timer@4001a000 {
            compatible = "nordic,nrf-timer";
            status = "disabled";
            reg = < 0x4001a000 0x1000 >;
            cc-num = < 0x6 >;
            max-bit-width = < 0x20 >;
            interrupts = < 0x1a 0x1 >;
            prescaler = < 0x0 >;
        };
        timer4: timer@4001b000 {
            compatible = "nordic,nrf-timer";
            status = "disabled";
            reg = < 0x4001b000 0x1000 >;
            cc-num = < 0x6 >;
            max-bit-width = < 0x20 >;
            interrupts = < 0x1b 0x1 >;
            prescaler = < 0x0 >;
        };
        pwm0: pwm@4001c000 {
            compatible = "nordic,nrf-pwm";
            reg = < 0x4001c000 0x1000 >;
            interrupts = < 0x1c 0x1 >;
            status = "okay";
            #pwm-cells = < 0x3 >;
            pinctrl-0 = < &pwm0_default >;
            pinctrl-1 = < &pwm0_sleep >;
            pinctrl-names = "default", "sleep";
            phandle = < 0xc >;
        };
        pdm0: pdm@4001d000 {
            compatible = "nordic,nrf-pdm";
            reg = < 0x4001d000 0x1000 >;
            interrupts = < 0x1d 0x1 >;
            status = "disabled";
        };
        acl: acl@4001e000 {
            compatible = "nordic,nrf-acl";
            reg = < 0x4001e000 0x1000 >;
            status = "okay";
        };
        flash_controller: flash-controller@4001e000 {
            compatible = "nordic,nrf52-flash-controller";
            reg = < 0x4001e000 0x1000 >;
            partial-erase;
            #address-cells = < 0x1 >;
            #size-cells = < 0x1 >;
            flash0: flash@0 {
                compatible = "soc-nv-flash";
                erase-block-size = < 0x1000 >;
                write-block-size = < 0x4 >;
                reg = < 0x0 0x100000 >;
                partitions {
                    compatible = "fixed-partitions";
                    #address-cells = < 0x1 >;
                    #size-cells = < 0x1 >;
                    boot_partition: partition@0 {
                        label = "mcuboot";
                        reg = < 0x0 0xc000 >;
                    };
                    slot0_partition: partition@c000 {
                        label = "image-0";
                        reg = < 0xc000 0x76000 >;
                    };
                    slot1_partition: partition@82000 {
                        label = "image-1";
                        reg = < 0x82000 0x76000 >;
                    };
                    storage_partition: partition@f8000 {
                        label = "storage";
                        reg = < 0xf8000 0x4000 >;
                    };
                };
            };
        };
        ppi: ppi@4001f000 {
            compatible = "nordic,nrf-ppi";
            reg = < 0x4001f000 0x1000 >;
            status = "okay";
        };
        mwu: mwu@40020000 {
            compatible = "nordic,nrf-mwu";
            reg = < 0x40020000 0x1000 >;
            status = "okay";
        };
        pwm1: pwm@40021000 {
            compatible = "nordic,nrf-pwm";
            reg = < 0x40021000 0x1000 >;
            interrupts = < 0x21 0x1 >;
            status = "disabled";
            #pwm-cells = < 0x3 >;
        };
        pwm2: pwm@40022000 {
            compatible = "nordic,nrf-pwm";
            reg = < 0x40022000 0x1000 >;
            interrupts = < 0x22 0x1 >;
            status = "disabled";
            #pwm-cells = < 0x3 >;
        };
        spi2: spi@40023000 {
            compatible = "nordic,nrf-spim";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40023000 0x1000 >;
            interrupts = < 0x23 0x1 >;
            max-frequency = < 0x7a1200 >;
            easydma-maxcnt-bits = < 0x10 >;
            status = "disabled";
        };
        rtc2: rtc@40024000 {
            compatible = "nordic,nrf-rtc";
            reg = < 0x40024000 0x1000 >;
            cc-num = < 0x4 >;
            interrupts = < 0x24 0x1 >;
            status = "disabled";
            clock-frequency = < 0x8000 >;
            prescaler = < 0x1 >;
        };
        i2s0: i2s@40025000 {
            compatible = "nordic,nrf-i2s";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40025000 0x1000 >;
            interrupts = < 0x25 0x1 >;
            status = "disabled";
        };
        usbd: zephyr_udc0: usbd@40027000 {
            compatible = "nordic,nrf-usbd";
            reg = < 0x40027000 0x1000 >;
            interrupts = < 0x27 0x1 >;
            num-bidir-endpoints = < 0x1 >;
            num-in-endpoints = < 0x7 >;
            num-out-endpoints = < 0x7 >;
            num-isoin-endpoints = < 0x1 >;
            num-isoout-endpoints = < 0x1 >;
            status = "okay";
            cdc_acm_uart0: cdc_acm_uart0 {
                compatible = "zephyr,cdc-acm-uart";
                current-speed = < 0x38400 >;
            };
        };
        uart1: uart@40028000 {
            compatible = "nordic,nrf-uarte";
            reg = < 0x40028000 0x1000 >;
            interrupts = < 0x28 0x1 >;
            status = "okay";
            current-speed = < 0x1c200 >;
            pinctrl-0 = < &uart1_default >;
            pinctrl-1 = < &uart1_sleep >;
            pinctrl-names = "default", "sleep";
            modem: modem {
                compatible = "quectel,bg600";
                mdm-power-gpios = < &gpio0 0x2 0x0 >;
                mdm-status-gpios = < &gpio1 0xd 0x0 >;
                mdm-dtr-gpios = < &gpio1 0x1 0x0 >;
                status = "okay";
                gnss: gnss {
                    compatible = "quectel,bg600-gnss";
                    status = "okay";
                };
                lte: lte {
                    compatible = "quectel,bg600-lte";
                    status = "okay";
                };
            };
        };
        qspi: qspi@40029000 {
            compatible = "nordic,nrf-qspi";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x40029000 0x1000 >, < 0x12000000 0x8000000 >;
            reg-names = "qspi", "qspi_mm";
            interrupts = < 0x29 0x1 >;
            status = "disabled";
        };
        pwm3: pwm@4002d000 {
            compatible = "nordic,nrf-pwm";
            reg = < 0x4002d000 0x1000 >;
            interrupts = < 0x2d 0x1 >;
            status = "disabled";
            #pwm-cells = < 0x3 >;
        };
        spi3: spi@4002f000 {
            compatible = "nordic,nrf-spim";
            #address-cells = < 0x1 >;
            #size-cells = < 0x0 >;
            reg = < 0x4002f000 0x1000 >;
            interrupts = < 0x2f 0x1 >;
            max-frequency = < 0x1e84800 >;
            easydma-maxcnt-bits = < 0x10 >;
            rx-delay-supported;
            rx-delay = < 0x2 >;
            status = "disabled";
        };
        gpio0: gpio@50000000 {
            compatible = "nordic,nrf-gpio";
            gpio-controller;
            reg = < 0x50000000 0x200 0x50000500 0x300 >;
            #gpio-cells = < 0x2 >;
            status = "okay";
            port = < 0x0 >;
            gpiote-instance = < &gpiote >;
            phandle = < 0x9 >;
        };
        gpio1: gpio@50000300 {
            compatible = "nordic,nrf-gpio";
            gpio-controller;
            reg = < 0x50000300 0x200 0x50000800 0x300 >;
            #gpio-cells = < 0x2 >;
            ngpios = < 0x10 >;
            status = "okay";
            port = < 0x1 >;
            gpiote-instance = < &gpiote >;
            phandle = < 0x4 >;
        };
        cryptocell: crypto@5002a000 {
            compatible = "nordic,cryptocell", "arm,cryptocell-310";
            reg = < 0x5002a000 0x1000 >, < 0x5002b000 0x1000 >;
            reg-names = "wrapper", "core";
            interrupts = < 0x2a 0x1 >;
            status = "okay";
        };
    };
    pinctrl: pin-controller {
        compatible = "nordic,nrf-pinctrl";
        i2c0_default: i2c0_default {
            phandle = < 0x2 >;
            group1 {
                psels = < 0x16002b >, < 0x18002a >;
                bias-pull-up;
            };
        };
        i2c0_sleep: i2c0_sleep {
            phandle = < 0x3 >;
            group1 {
                psels = < 0x16002b >, < 0x18002a >;
            };
        };
        uart0_default: uart0_default {
            group1 {
                psels = < 0x4 >, < 0x401ff >;
            };
            group2 {
                psels = < 0x2001a >, < 0x601ff >;
            };
        };
        uart1_default: uart1_default {
            phandle = < 0x7 >;
            group1 {
                psels = < 0x27 >, < 0x20024 >, < 0x401ff >, < 0x601ff >;
            };
        };
        uart1_sleep: uart1_sleep {
            phandle = < 0x8 >;
            group1 {
                psels = < 0x27 >, < 0x20024 >;
                low-power-enable;
                bias-disable;
            };
        };
        pwm0_default: pwm0_default {
            phandle = < 0x5 >;
            group1 {
                psels = < 0x2c0023 >;
            };
        };
        pwm0_sleep: pwm0_sleep {
            phandle = < 0x6 >;
            group1 {
                psels = < 0x2c0023 >;
                low-power-enable;
            };
        };
    };
    rng_hci: entropy_bt_hci {
        compatible = "zephyr,bt-hci-entropy";
        status = "okay";
    };
    sw_pwm: sw-pwm {
        compatible = "nordic,nrf-sw-pwm";
        status = "disabled";
        generator = < &timer1 >;
        clock-prescaler = < 0x0 >;
        #pwm-cells = < 0x3 >;
    };
    cpus {
        #address-cells = < 0x1 >;
        #size-cells = < 0x0 >;
        cpu@0 {
            device_type = "cpu";
            compatible = "arm,cortex-m4f";
            reg = < 0x0 >;
            #address-cells = < 0x1 >;
            #size-cells = < 0x1 >;
            itm: itm@e0000000 {
                compatible = "arm,armv7m-itm";
                reg = < 0xe0000000 0x1000 >;
                swo-ref-frequency = < 0x1e84800 >;
            };
        };
    };
    zephyr,user {
        usb-gpios = < &gpio1 0x9 0x11 >;
    };
    pwmleds {
        compatible = "pwm-leds";
        pwm_led0: pwm_led_0 {
            pwms = < &pwm0 0x0 0x1312d00 0x0 >;
        };
    };
};

[Susheel Nuguru]

Hmm, 

Looking at the driver file zephyr\drivers\serial\uart_nrfx_uart.c, it looks like it has implemented the support for disable_rx but nothing for low_power_enable. You can see that the low-power-enable is not even extracted from the device node. 

So in short, I think it looks like low-power-enable is not yet supported in nRF driver. 

[Syl20D]

Ok, did you have a workaround to disable rx or uart dynamically?

[Susheel Nuguru]

No, we do not seem to support it. The workaround is to implement it in the driver. Will be a feature request.

[Syl20D]

I've succeed to have the desired power consumption when I reset the RXD EasyDMA register.

Can the DMA force the input connexion buffer?

[Susheel Nuguru]

Syl20D said:

I've succeed to have the desired power consumption when I reset the RXD EasyDMA register.

can you show me some code snippets on how you did that?