From 3dcf412a02bb9f12c5ec4a7151523962f508906b Mon Sep 17 00:00:00 2001
From: Thomas Kolb <cfr34k-git@tkolb.de>
Date: Sat, 8 Oct 2022 21:48:43 +0200
Subject: [PATCH] BMP280: Crude workaround for detecting chip presence

---
 src/bmp280.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/bmp280.c b/src/bmp280.c
index e26e70c..1526fb8 100644
--- a/src/bmp280.c
+++ b/src/bmp280.c
@@ -45,6 +45,23 @@ bool bmp280_init(void)
 	uint8_t rdata[32];
 	uint8_t wsize, rsize;
 
+	// check for chip presence by accessing the chip id register (not a proper read!)
+	i2c_set_7bit_address(I2C1, BMP280_7BIT_ADDR);
+	i2c_set_write_transfer_dir(I2C1);
+	i2c_set_bytes_to_transfer(I2C1, 1);
+	i2c_enable_autoend(I2C1);
+	i2c_send_start(I2C1);
+
+	uint32_t timeout = 1000000;
+	while(--timeout && !i2c_transmit_int_status(I2C1)); // wait for the address transfer to complete
+
+	i2c_send_data(I2C1, 0xD0);
+
+	if((timeout == 0) || i2c_nack(I2C1)) {
+		// something went wrong during communication
+		goto err_out;
+	}
+
 	// read the chip ID
 	wsize = 0;
 	wdata[wsize++] = 0xD0;