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examples/sdmmc: enable internal pull-ups in SD mode

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Some development boards do not have sufficient external pull-ups on
SD card pins. Most notably, if high level on GPIO13 is not registered
by the card when GO_IDLE_STATE command is received, the card will enter
SPI mode and further communication will not be possible, until power to
the card is toggled.

This change enables internal pull-ups on SD card pins in an attempt to
make this initialization process more reliable.
This commit is contained in:
Ivan Grokhotkov 2017-10-13 08:21:06 +08:00
parent 3cf23ff77d
commit a5f96b22d1
1 changed files with 9 additions and 0 deletions
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9
examples/storage/sd_card/main/sd_card_example_main.c
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@ -54,6 +54,15 @@ void app_main(void)
// Modify slot_config.gpio_cd and slot_config.gpio_wp if your board has these signals.
sdmmc_slot_config_t slot_config = SDMMC_SLOT_CONFIG_DEFAULT();
// GPIOs 15, 2, 4, 12, 13 should have external 10k pull-ups.
// Internal pull-ups are not sufficient. However, enabling internal pull-ups
// does make a difference some boards, so we do that here.
gpio_set_pull_mode(15, GPIO_PULLUP_ONLY); // CMD, needed in 4- and 1- line modes
gpio_set_pull_mode(2, GPIO_PULLUP_ONLY); // D0, needed in 4- and 1-line modes
gpio_set_pull_mode(4, GPIO_PULLUP_ONLY); // D1, needed in 4-line mode only
gpio_set_pull_mode(12, GPIO_PULLUP_ONLY); // D2, needed in 4-line mode only
gpio_set_pull_mode(13, GPIO_PULLUP_ONLY); // D3, needed in 4- and 1-line modes
#else
ESP_LOGI(TAG, "Using SPI peripheral");