Melzi has a 1284 (#16090)

platformio.ini

 #
 [env:melzi]
 platform      = atmelavr
-board         = sanguino_atmega644p
+board         = sanguino_atmega1284p
 lib_deps      = ${common.lib_deps}
   TMC26XStepper=https://github.com/trinamic/TMC26XStepper/archive/master.zip
 src_filter    = ${common.default_src_filter} +<src/HAL/HAL_AVR>
 #
 [env:melzi_optiboot]
 platform      = atmelavr
-board         = sanguino_atmega644p
+board         = sanguino_atmega1284p
 lib_deps      = ${common.lib_deps}
   TMC26XStepper=https://github.com/trinamic/TMC26XStepper/archive/master.zip
 src_filter    = ${common.default_src_filter} +<src/HAL/HAL_AVR>