diff --git a/main.c b/main.c
index f83649c..1e87483 100644
--- a/main.c
+++ b/main.c
@@ -8,6 +8,7 @@
 
 #include "stm8s.h"
 #include "main.h"
+#include "softi2c_master.h"
 
 #define EEPROM_ADDR 0x4000 // EEPROM start address
 // LED pin (sink for on)
@@ -185,9 +186,48 @@ level pulse on the Hot Plug Detect pin. This pulse shall be at least 100 msec.
 	}
 
 	rim(); // re-enable interrupts
+	// even if we don't pull up HPD ourself, we should be able to respond to I²C within 20 ms
+	puts("I²C ready\r\n");
+
+	// read sink EDID
+	if (!i2c_fwd) { // ensure we are the only master on the I²C sink lines
+		IWDG_KR = IWDG_KR_KEY_REFRESH; // reset watchdog
+		puts("reading sink EDID: ");
+		softi2c_master_setup(100); // start the I²C master to talk to sink
+		bool i2c_success = false; // if the complete read succeeded
+		if (!softi2c_master_start()) { // start transaction
+			goto i2c_end;
+		}
+		if (!softi2c_master_select_slave(0x50, true)) { // select EDID
+			goto i2c_end;
+		}
+		const uint8_t edid_addr = 0x00; // EDID address to read
+		if (!softi2c_master_write(&edid_addr, 1)) { // write address to read
+			goto i2c_end;
+		}
+		if (!softi2c_master_start()) { // re-start transaction
+			goto i2c_end;
+		}
+		if (!softi2c_master_select_slave(0x50, false)) { // re-select EDID
+			goto i2c_end;
+		}
+		uint8_t edid_sink[256]; // buffer for sink EDID
+		if (!softi2c_master_read(edid_sink, ARRAY_LENGTH(edid_sink))) { // read EDID
+			goto i2c_end;
+		}
+		i2c_success = true; // complete read succeeded
+i2c_end:
+		softi2c_master_stop();
+		if (i2c_success) {
+			puts("success\r\n");
+		} else {
+			puts("fail\r\n");
+		}
+	}
+
 	bool action = false; // if an action has been performed
 	LED_PORT->ODR.reg &= ~LED_PIN; // switch LED on to indicate we are ready
-	puts("ready\r\n");
+	puts("loop\r\n");
 	while (true) {
 		IWDG_KR = IWDG_KR_KEY_REFRESH; // reset watchdog
 		if (i2c_transaction_new) { // an I²C transaction started