SPM works!

Self programming works
Sketch can be uploaded as bootloader directly from Arduino (using external programmer)
Updated Readme
Code is even smaller than previously
Cleaned up Writer (and changed baudrate)
Added LED to Reader to indicate bootloader working (only for testing)

Author: marecl

MULoaderReader/MULoaderReader.ino

@@ -1,30 +1,36 @@
 #include <SPI.h>
 #include "RC522.h"
+#include <Arduino.h>
 #include <avr/boot.h>
 
-/* Move this to AVR Studio */
-
-#define S_DEBUG
+/* 3760 bytes free after removing serial */
+/* Compared with 5624 bytes it's a huge difference */
+//#define S_DEBUG
 
 void setup() {
-  RC522 rfid(10);
+  cli();
+  pinMode(A1, OUTPUT);
+  digitalWrite(A1, HIGH);
   SPI.begin();
+  RC522 rfid(10);
+  rfid.PCD_Init();
+
 #ifdef S_DEBUG
-  Serial.begin(2000000);
+  Serial.begin(115200);
   Serial.println(F("MostUseless Bootloader Reader"));
 #endif
-  rfid.PCD_Init();
-
-  RC522::MIFARE_Key key;
-  memset(key.keyByte, 0xFF, 6);
-
 
   /* Jump to code after timeout */
-  while (millis() < 10000 && !rfid.PICC_IsNewCardPresent());
-  if (millis() > 10000) asm("jmp 0x0000");
-
+  /* Timeout doesn't work but lol, the rest of stuff works */
+  while (millis() < 1000 && !rfid.PICC_IsNewCardPresent());
+  if (millis() >= 1000) {
+    digitalWrite(A1, LOW);
+    asm("jmp 0");
+  }
   while (!rfid.PICC_ReadCardSerial());
 
+  digitalWrite(A1, LOW);
+
   /* Sketch metadata */
   uint16_t siz = 0;
   uint8_t parts = 0;
@@ -38,15 +44,19 @@ void setup() {
   uint8_t memptr = 0;
 
   /*
-      We don't need to worry about extra data in last
-      page if we already set buffer as empty :)
+    We don't need to worry about extra data in last
+    page if we already set buffer as empty :)
   */
-  uint8_t pageBuffer[256];
+  volatile static uint8_t pageBuffer[256];
   memset(pageBuffer, 0xFF, 256);
 
+  /* Generic key */
+  RC522::MIFARE_Key key;
+  memset(key.keyByte, 0xFF, 6);
+
   /*
-      Reading every block and using page offset
-      to save progress if more parts are needed
+    Reading every block and using page offset
+    to save progress if more parts are needed
   */
 
   for (uint8_t block = 1; block < blocks; block++) {
@@ -56,18 +66,18 @@ void setup() {
     }
 
     uint8_t buffer[18];
-    const byte len = 18;
+    byte len = 18;
 
     rfid.PCD_Authenticate(RC522::PICC_CMD_MF_AUTH_KEY_A, block, &key, &(rfid.uid));
     rfid.MIFARE_Read(block, buffer, &len);
 
     /*
-        2 bytes - code size
-        1 byte - parts [token]
-        1 byte - full pages (including not full)
-        1 byte - amount of data in last page
-        1 byte - full blocks
-        1 byte - amount of data in last block
+      2 bytes - code size
+      1 byte - parts [token]
+      1 byte - full pages (including not full)
+      1 byte - amount of data in last page
+      1 byte - full blocks
+      1 byte - amount of data in last block
     */
     if (block == 1) {
       siz = word(buffer[0], buffer[1]);
@@ -117,18 +127,48 @@ void setup() {
 #endif
 
     /* Write each page to flash */
-    /* 3888 bytes free after removing serial */
-
-
+    digitalWrite(A1, HIGH);
+    boot_program_page(memptr, pageBuffer);
 
     /* Finished writing to flash */
-    memptr++;
+    memptr += 256;
     memset(pageBuffer, 0xFF, 256);
   }
   rfid.PICC_HaltA();
   rfid.PCD_StopCrypto1(); // Stop encryption on PCD
+  rfid.PCD_AntennaOff();
+
+  digitalWrite(A1, LOW);
+  asm("jmp 0");
+}
+
+void boot_program_page(uint32_t page, uint8_t *buf) {
+  uint16_t i;
+  uint8_t sreg;
+
+  sreg = SREG;
+  cli();
+
+  eeprom_busy_wait();
+
+  boot_page_erase(page);
+  boot_spm_busy_wait();
+  for (i = 0; i < SPM_PAGESIZE; i += 2)
+  {
+    uint16_t w = *buf++;
+    w += (*buf++) << 8;
+    boot_page_fill(page + i, w);
+  }
+
+  boot_page_write(page); // Store buffer in flash page.
+  boot_spm_busy_wait(); // Wait until the memory is written.
+
+  // Reenable RWW-section again. We need this if we want to jump back
+  // to the application after bootloading.
+  boot_rww_enable();
 
-  asm("jmp 0x0000");
+  // Re-enable interrupts (if they were ever enabled).
+  SREG = sreg;
 }
 
 void loop() {

MULoaderReader/RC522.h

@@ -1,18 +1,12 @@
 #ifndef RC522_h
 #define RC522_h
-#define __STDC_LIMIT_MACROS
-#include <stdint.h>
-#include <Arduino.h>
 #include <SPI.h>
 #ifndef RC522_SPICLOCK
 #define RC522_SPICLOCK SPI_CLOCK_DIV4
 #endif
 
 class RC522 {
   public:
-    //static constexpr byte FIFO_SIZE = 64;
-    //static constexpr uint8_t UNUSED_PIN = UINT8_MAX;
-
     enum PCD_Register : byte {
       CommandReg = 0x01 << 1,
       ComIEnReg = 0x02 << 1,

MULoaderReader/platform.local.txt

@@ -0,0 +1,7 @@
+compiler.c.extra_flags=-Xlinker .text=0x7000
+compiler.c.elf.extra_flags=-Ttext 0x7000 
+compiler.S.extra_flags=-Xlinker .text=0x7000
+compiler.cpp.extra_flags=-Xlinker .text=0x7000
+compiler.ar.extra_flags=
+compiler.objcopy.eep.extra_flags=
+compiler.elf2hex.extra_flags=

MULoaderWriter/MULoaderWriter.ino

@@ -7,90 +7,11 @@ MFRC522 rfid(10, 9);
 /*
    YES, IT HAS TO BE THIS LONG
 */
-byte prog[] = {0x01, 0xE0, 0x07, 0x07, 0x08, 0xB9, 0xFE, 0xCF,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD, 0xDD,
-               0xDD, 0xDD, 0xDD, 0xDD, 0xDD
+byte prog[] = {0x01, 0xE0, 0x07, 0xB9, 0x08, 0xB9, 0xFE, 0xCF
               };
 
 void setup() {
-  Serial.begin(2000000);
+  Serial.begin(115200);
   SPI.begin();
   rfid.PCD_Init();
   rfid.PCD_DumpVersionToSerial();

README.md

@@ -18,7 +18,8 @@ It's not end yet, block #0 is *NOT* meant for data storage, so all in all, inste
 During development I decided to take away one more block for sketch metadata (number of parts, code size etc) so we end up with 736 bytes of storage available per 1k tag (also it makes code a bit smaller, yay!).  
 Luckily this is only for the first tag, the rest of tags will probably be able to store 752 bytes **(whole 16 bytes more)**.
 
-Full 28672 byte code (in the worst case) will take up to 40 tags. Don't forget, that they will have to be scanned in specific order or your uC will crash at some point.
+Full 28672 byte code (in the worst case) will take up to 40 tags. Don't forget, that they will have to be scanned in specific order or your uC will crash at some point.  
+I don't know why, but millis() is not working, but I cannot override them, because they're already defined ¯\_(ツ)_/¯
 
 Also, I didn't have any experience in working with AVR bootloaders nor RFID tags.
 
@@ -34,6 +35,13 @@ N/A
 * MFRC522 reader from China (the working one)
 * Breadboard and some jumper wires
 * MIFARE Classic 1k tags (plenty of them)
+* External programmer (USBasp or AVRispmkII)
+
+Fuse bits:
+* Low: 0xFF
+* High: 0xD8
+* Extended: FD
+* Lock: 3F
 
 |Arduino|MFRC522|
 |-------|-------|
@@ -45,24 +53,27 @@ N/A
 |  GND  |  GND  |
 |  3V3  |  3V3  |
 
-Reset circuit like this allowed to slim code a bit and as far as I see causes no problems so... It's working?
+Reset circuit like this allowed to slim code a bit and as far as I see causes no problems so... It's working?  
+I added an LED on A1 to watch if flash is being updated.  
+Test code lights up LED on A0.  
 
 ### Software
 1. Compile whatever you want for Arduino
 2. Convert compiled code to C array
 3. Add this array to Writer source and upload to Arduino
 4. Scan tag and pray it transferred correctly (because there is no verification)
-5. Upload MULoaderReader to target
-6. Scan tag and watch stuff appearing in Serial Monitor
+5. Copy platform.local.txt to arduino/hardware/avr/[version] (remember to use it only with Reader)
+6. Upload MULoaderReader to target
+7. Scan tag and watch stuff appearing in Serial Monitor
 
 Remember to uncomment define at the beginning of Reader code, otherwise you won't see anything :)
 
 ### What works
 * Uploading to tag (one)
 * Reading from tag
-* I know how to use SPM
+* Updating flash
 
 ### What doesn't work
 * Serial upload to tag (because I didn't implement it yet)
-* Bootloading uC with MULoaderReader (too big and stuff)
 * Programming tags in parts of 736 bytes
+* Bootloader timeout

Tests/blink.c

@@ -0,0 +1,3 @@
+:020000020000FC
+:0800000001E007B908B9FECFC9
+:00000001FF