diff --git a/rfid/t5577/protocol_demo1.c b/rfid/t5577/protocol_demo1.c
new file mode 100644
index 0000000..156075a
--- /dev/null
+++ b/rfid/t5577/protocol_demo1.c
@@ -0,0 +1,140 @@
+/**
+ * @file protocol_demo1.c
+ * @brief Demo protocol, doesn't do read/emulate, but does write data to the T5577 tag.
+ * @details This protocol is a demo protocol that doesn't actually do any reading or
+ * emulating, but does write data to the T5577 tag.  This is useful for testing the
+ * write functionality of the T5577 tag.  You can change the data in the write_data
+ * function to write different data to the T5577 tag.
+ * 
+ * A sample file looks like (test.rfid):
+ * Filetype: Flipper RFID key
+ * Version: 1
+ * Key type: Demo1
+ * Data: 42 13
+ * 
+ * You can also go to 125 kHz RFID, Add Manually, Derek Jamison Demo1, enter the
+ * data "42 13", click save, choose a name, and click save again.  This will create
+ * the test.rfid file.
+ * 
+ * For more information, see the youtube video at https://youtu.be/nSCIOz2bVR0
+*/
+#include <furi.h>
+#include <toolbox/protocols/protocol.h>
+#include <bit_lib/bit_lib.h>
+#include "lfrfid_protocols.h"
+
+#define TAG "Demo1"
+
+#define DEMO1_DECODED_DATA_SIZE (2)
+
+typedef struct {
+    uint8_t data[DEMO1_DECODED_DATA_SIZE];
+    uint32_t feed_counter;
+} ProtocolDemo1;
+
+ProtocolDemo1* protocol_demo1_alloc(void) {
+    ProtocolDemo1* protocol = malloc(sizeof(ProtocolDemo1));
+    return protocol;
+};
+
+void protocol_demo1_free(ProtocolDemo1* protocol) {
+    free(protocol);
+};
+
+uint8_t* protocol_demo1_get_data(ProtocolDemo1* protocol) {
+    return protocol->data;
+};
+
+void protocol_demo1_decoder_start(ProtocolDemo1* protocol) {
+    // This would normally reset the decoder state (clearing encoded_data).
+    protocol->feed_counter = 0;
+};
+
+bool protocol_demo1_decoder_feed(ProtocolDemo1* protocol, bool level, uint32_t duration) {
+    // Normally, we would decode the data here & see if the data looks like a full packet.
+    // NOTE: duration is in us.
+    // When it does, you would return true.
+    UNUSED(level);
+    UNUSED(duration);
+
+    // Prints "data: [0]:42 [1]:13" to the log for our sample file.
+    FURI_LOG_D(TAG, "data: [0]:%02x [1]:%02x", protocol->data[0], protocol->data[1]);
+    if(protocol->data[0] == 0x42) {
+        protocol->feed_counter++;
+    }
+
+    return protocol->feed_counter % 100 == 99;
+};
+
+bool protocol_demo1_encoder_start(ProtocolDemo1* protocol) {
+    // This would normally reset the encoder state (populating encoded_data).
+    UNUSED(protocol);
+    return true;
+};
+
+LevelDuration protocol_demo1_encoder_yield(ProtocolDemo1* protocol) {
+    // This would normally return the next level/duration pair to send.
+    // Note: duration is in ticks (8us).
+    UNUSED(protocol);
+    return level_duration_make(true, 1);
+};
+
+void protocol_demo1_render_data(ProtocolDemo1* protocol, FuriString* result) {
+    // This would normally use protocol->data to populate the result string.
+    UNUSED(protocol);
+    furi_string_printf(result, "ATA5577 Maker %02x %02x", protocol->data[0], protocol->data[1]);
+}
+
+void protocol_demo1_render_brief_data(ProtocolDemo1* protocol, FuriString* result) {
+    // This would normally use protocol->data to populate the brief result string.
+    UNUSED(protocol);
+    furi_string_printf(result, "T5577 %02x %02x", protocol->data[0], protocol->data[1]);
+}
+
+bool protocol_demo1_write_data(ProtocolDemo1* protocol, void* data) {
+    LFRFIDWriteRequest* request = (LFRFIDWriteRequest*)data;
+    bool result = false;
+
+    protocol_demo1_encoder_start(protocol);
+
+    // This would normally write the data to the T5577 using the data
+    // from the protocol->encoded_data.  For this demo, we'll just
+    // populate the request with some known data.
+    //
+    // We use the data from https://youtu.be/5DvIBvXBDX8?t=367
+
+    if(request->write_type == LFRFIDWriteTypeT5577) {
+        request->t5577.block[0] = LFRFID_T5577_MODULATION_FSK2a | LFRFID_T5577_BITRATE_RF_50 |
+                                  (3 << LFRFID_T5577_MAXBLOCK_SHIFT);
+        request->t5577.block[1] = 0x1D555955;
+        request->t5577.block[2] = 0x5569A599;
+        request->t5577.block[3] = 0xA96A995A;
+        request->t5577.blocks_to_write = 4;
+        result = true;
+    }
+    return result;
+};
+
+const ProtocolBase protocol_demo1 = {
+    .name = "Demo1",
+    .manufacturer = "Derek Jamison",
+    .data_size = DEMO1_DECODED_DATA_SIZE,
+    .features = LFRFIDFeatureASK,
+    .validate_count = 2,
+    .alloc = (ProtocolAlloc)protocol_demo1_alloc,
+    .free = (ProtocolFree)protocol_demo1_free,
+    .get_data = (ProtocolGetData)protocol_demo1_get_data,
+    .decoder =
+        {
+            .start = (ProtocolDecoderStart)protocol_demo1_decoder_start,
+            .feed = (ProtocolDecoderFeed)protocol_demo1_decoder_feed,
+        },
+    .encoder =
+        {
+            .start = (ProtocolEncoderStart)protocol_demo1_encoder_start,
+            .yield = (ProtocolEncoderYield)protocol_demo1_encoder_yield,
+        },
+    .render_data = (ProtocolRenderData)protocol_demo1_render_data,
+    .render_brief_data = (ProtocolRenderData)protocol_demo1_render_brief_data,
+    .write_data = (ProtocolWriteData)protocol_demo1_write_data,
+};
diff --git a/rfid/t5577/protocol_demo1.h b/rfid/t5577/protocol_demo1.h
new file mode 100644
index 0000000..fb22b47
--- /dev/null
+++ b/rfid/t5577/protocol_demo1.h
@@ -0,0 +1,4 @@
+#pragma once
+#include <toolbox/protocols/protocol.h>
+
+extern const ProtocolBase protocol_demo1;
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