ESP32: configurable SPI speed for SD-card

folkertvanheusden · Nov 6, 2024 · 78c8512 · 78c8512
1 parent 27e7ac4
commit 78c8512
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Showing 4 changed files with 34 additions and 20 deletions.
diff --git a/microcontrollers/backend-sdcard.cpp b/microcontrollers/backend-sdcard.cpp
@@ -17,14 +17,15 @@
 
 extern void write_led(const int gpio, const int state);
 
-backend_sdcard::backend_sdcard(const int led_read, const int led_write, const int pin_SD_MISO, const int pin_SD_MOSI, const int pin_SD_SCLK, const int pin_SD_CS):
+backend_sdcard::backend_sdcard(const int led_read, const int led_write, const int pin_SD_MISO, const int pin_SD_MOSI, const int pin_SD_SCLK, const int pin_SD_CS, const std::optional<int> spi_speed):
 	backend("SD-card"),
 	led_read(led_read),
 	led_write(led_write),
 	pin_SD_MISO(pin_SD_MISO),
 	pin_SD_MOSI(pin_SD_MOSI),
 	pin_SD_SCLK(pin_SD_SCLK),
-	pin_SD_CS(pin_SD_CS)
+	pin_SD_CS(pin_SD_CS),
+	spi_speed(spi_speed)
 {
 #if defined(RP2040W)
 	mutex_init(&serial_access_lock);
@@ -64,24 +65,29 @@ bool backend_sdcard::reinit(const bool close_first)
 	bool ok = false;
 	SPI.begin(pin_SD_SCLK, pin_SD_MISO, pin_SD_MOSI, pin_SD_CS);
 #if defined(WT_ETH01)
-	for(int sp=22; sp>=14; sp -= 2) {
-		Serial.printf("Trying %d MHz...\r\n", sp);
-		if (sd.begin(SdSpiConfig(pin_SD_CS, SHARED_SPI, SD_SCK_MHZ(sp)))) {
-			ok = true;
-			Serial.printf("Accessing SD card at %d MHz\r\n", sp);
-			break;
-		}
-	}
+	const int start_speed = 22;
+	const int end_speed   = 14;
+	const int steps       = 2;
 #else
-	for(int sp=50; sp>=14; sp -= 4) {
-		Serial.printf("Trying %d MHz...\r\n", sp);
-		if (sd.begin(SdSpiConfig(pin_SD_CS, SHARED_SPI, SD_SCK_MHZ(sp)))) {
-			ok = true;
-			Serial.printf("Accessing SD card at %d MHz\r\n", sp);
-			break;
+	const int start_speed = 50;
+	const int end_speed   = 14;
+	const int steps       = 4;
+#endif
+	if (spi_speed.has_value()) {
+		ok = sd.begin(SdSpiConfig(pin_SD_CS, SHARED_SPI, SD_SCK_MHZ(spi_speed.value())));
+		if (ok)
+			Serial.printf("Accessing SD card at %d MHz\r\n", spi_speed.value());
+	}
+	else {
+		for(int sp=start_speed; sp>=end_speed; sp -= steps) {
+			Serial.printf("Trying %d MHz...\r\n", sp);
+			if (sd.begin(SdSpiConfig(pin_SD_CS, SHARED_SPI, SD_SCK_MHZ(sp)))) {
+				ok = true;
+				Serial.printf("Accessing SD card at %d MHz\r\n", sp);
+				break;
+			}
 		}
 	}
-#endif
 
 	if (ok == false) {
 		Serial.printf("SD-card mount failed (assuming CS is on pin %d)\r\n", pin_SD_CS);

diff --git a/microcontrollers/backend-sdcard.h b/microcontrollers/backend-sdcard.h
@@ -1,4 +1,5 @@
 #include <mutex>
+#include <optional>
 #if defined(WT_ETH01)
 #define SPI_DRIVER_SELECT 1
 #endif
@@ -20,6 +21,7 @@ class backend_sdcard : public backend
 	const int    pin_SD_MOSI { -1 };
 	const int    pin_SD_SCLK { -1 };
 	const int    pin_SD_CS   { -1 };
+	const std::optional<int> spi_speed;
 
 #if defined(RP2040W)
 	mutex_t    serial_access_lock;
@@ -33,7 +35,7 @@ class backend_sdcard : public backend
 	void wait_for_card();
 
 public:
-	backend_sdcard(const int led_read, const int led_write, const int pin_SD_MISO, const int pin_SD_MOSI, const int pin_SD_SCLK, const int pin_SD_CS);
+	backend_sdcard(const int led_read, const int led_write, const int pin_SD_MISO, const int pin_SD_MOSI, const int pin_SD_SCLK, const int pin_SD_CS, const std::optional<int> spi_speed);
 	virtual ~backend_sdcard();
 
 	bool begin() override;

diff --git a/microcontrollers/data/cfg-iESP.json.example b/microcontrollers/data/cfg-iESP.json.example
@@ -15,5 +15,6 @@
 	"SD-MISO": 19,
 	"SD-MOSI": 23,
 	"SD-SCLK": 18,
-	"SD-CS": 5
+	"SD-CS": 5,
+	"spi-speed": 16
 }
diff --git a/microcontrollers/main.ino b/microcontrollers/main.ino
@@ -90,11 +90,13 @@ int pin_SD_MISO= -1;
 int pin_SD_MOSI= -1;
 int pin_SD_SCLK= -1;
 int pin_SD_CS  = -1;
+std::optional<int> spi_speed { 14 };
 #else
 int pin_SD_MISO= 19;
 int pin_SD_MOSI= 23;
 int pin_SD_SCLK= 18;
 int pin_SD_CS  =  5;
+std::optional<int> spi_speed;
 #endif
 
 snmp      *snmp_      { nullptr };
@@ -278,6 +280,9 @@ bool load_configuration() {
 	if (cfg.containsKey("log-level"))
 		logging::log_level_syslog = logging::parse_ll(cfg["log-level"].as<std::string>());
 
+	if (cfg.containsKey("spi-speed"))
+		spi_speed = cfg["spi-speed"].as<int>();
+
 	data_file.close();
 
 #if !defined(TEENSY4_1)
@@ -638,7 +643,7 @@ void setup() {
 	bs = new backend_sdcard_teensy41(led_green, led_yellow);
 #else
   Serial.printf("LEDgreen: %d, LEDyellow: %d, MISO: %d, MOSI: %d, SCLK: %d, CS: %d\r\n", led_green, led_yellow, pin_SD_MISO, pin_SD_MOSI, pin_SD_SCLK, pin_SD_CS);
-	bs = new backend_sdcard(led_green, led_yellow, pin_SD_MISO, pin_SD_MOSI, pin_SD_SCLK, pin_SD_CS);
+	bs = new backend_sdcard(led_green, led_yellow, pin_SD_MISO, pin_SD_MOSI, pin_SD_SCLK, pin_SD_CS, spi_speed);
 #endif
 
 	draw_status(13);