Power optimization - Improve SPI sleep mode #1758
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Ensure that all pins are set to their default configuration during sleep mode. Disable the workaround for FTPAN58 (SPI freezes when transfering a single byte) at the end of the transfer. This disables the resources needed for the workaround. Those changes reduce the power usage by 430-490µA.
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Build size and comparison to main:
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commit 5587ce3 Author: Jean-François Milants <jf@codingfield.com> Date: Sun May 7 18:24:34 2023 +0200 Power optimization - Improve SPI sleep mode Ensure that all pins are set to their default configuration during sleep mode. Disable the workaround for FTPAN58 (SPI freezes when transfering a single byte) at the end of the transfer. This disables the resources needed for the workaround. Those changes reduce the power usage by 430-490µA.
This PR basically contains 2 changes : reset the CS pin configuration during sleep (and restore it at wake up) and disable the "workaround for FTPAN58" (disable the PPI channel). As I said in responses to your reviews, resetting the CS pin config is probably wrong as CS pins must be kept high whenever we don't want devices to listen to the bus, so I'll remove those change. Most of the power usage reduction comes from disabling the PPI channel : from 900µA to 410µA in sleep mode with BLE disabled. |
Calls to Spi::Init() are not needed, pin initialization is already done in ctor(). Remove calls to Spi::Sleep()/Spi::Wakeup() to ensure that SPI CS pins are kept high even in sleep mode.
ST7789 driver : replace the constant '26' with a named constant to specify the pin number of the reset pin of the LCD controller.
Fix formatting issue in St7789.cpp
| void St7789::HardwareReset() { | ||
| nrf_gpio_pin_clear(26); | ||
| nrf_gpio_pin_clear(pinReset); | ||
| nrf_delay_ms(10); | ||
| nrf_gpio_pin_set(26); | ||
| nrf_gpio_pin_set(pinReset); | ||
| } |
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Can we configure the pin only at the beginning of this function, and reset back to default before returning?
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The pins needs to be kept at a high level to ensure the display controller won't reset unexpectedly, so I guess we can't configure the pins to default (input, no pull up/down) here.
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If that's true, wouldn't that mean we shouldn't default configure the pin in the sleep function either or anywhere else?
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Yes, you are right, I fixed this in 3c668ca.
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No, there's still nrf_gpio_cfg_default in the St7789::Sleep() function.
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Yes, right, I guess we shouldn't default the reset pin!
Fix RecoveryLoader.
commit 5587ce3 Author: Jean-François Milants <jf@codingfield.com> Date: Sun May 7 18:24:34 2023 +0200 Power optimization - Improve SPI sleep mode Ensure that all pins are set to their default configuration during sleep mode. Disable the workaround for FTPAN58 (SPI freezes when transfering a single byte) at the end of the transfer. This disables the resources needed for the workaround. Those changes reduce the power usage by 430-490µA.
As of InfiniTimeOrg/InfiniTime#1758 ST7789 driver constructor has a pinReset argument.
As of InfiniTimeOrg/InfiniTime#1758 ST7789 driver constructor has a pinReset argument. Update the InfiniTime submodule to the state after the update of the ST7789 driver. Fixes: InfiniTimeOrg#107
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Thanks for these improvements! It seems like my pinetime is really holding out very long on one charge now, I am very happy about that. 😊 |
Ensure that all pins are set to their default configuration during sleep mode. Disable the workaround for FTPAN58 (SPI freezes when transfering a single byte) at the end of the transfer. This disables the resources needed for the workaround. Those changes reduce the power usage by 430-490µA.