Board XY LPWM

Note: thanks to @plumbum for reverse-engineering, writing board support code and writing initial documentation!

LCD and LCD-Controller

HT1621B segments map

; addr  b3      b2      b1      b0
; -------------------------------------
;  0    2.1A    2.1F    2.1E    2.1D
;  1    2.1B    2.1G    2.1C    2.1dot
;  2    2.2A    2.2F    2.2E    2.2D
;  3    2.2B    2.2G    2.2C    2.2dot
;  4    2.3A    2.3F    2.3E    2.3D
;  5    2.3B    2.3G    2.3C    2.3dot
;  6    2.4A    2.4F    2.4E    2.4D
;  7    2.4B    2.4G    2.4C    2.colon
;  8    2.W     2.%     2.h     2.A(mp)
;  9    1.4B    1.4G    1.4C    1.V
; 10    1.4A    1.4F    1.4E    1.4D
; 11    1.3B    1.3G    1.3C    1.3dot
; 12    1.3A    1.3F    1.3E    1.3D
; 13    1.2B    1.2G    1.2C    1.2dot
; 14    1.2A    1.2F    1.2E    1.2D
; 15    1.1B    1.1G    1.1C    1.1dot
; 16    1.1A    1.1F    1.1E    1.1D
; 17    1.IN    1.OUT   2.SET   1.°C

LCD FONT:

; 2.             !    "    #    $    %    &    '    (    )    *    +    ,    -    .    /
        .db      0x60,0x48,0x7E,0xD6,0x46,0xFC,0x08,0xF0,0x9A,0xCC,0x0c,0x02,0x04,0x02,0x28
; 3.        0    1    2    3    4    5    6    7    8    9    :    ;    <    =    >    ?
        .db 0xFA,0x0A,0xBC,0x9E,0x4E,0xD6,0xF6,0x8A,0xFE,0xDE,0x00,0x00,0x30,0x14,0x88,0xAC
; 4.        @    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O
        .db 0xBE,0xEE,0x76,0x34,0x3E,0xF4,0xE4,0xF2,0x66,0x60,0x1A,0x7C,0x70,0xA6,0x26,0x36
; 5.        P    Q    R    S    T    U    V    W    X    Y    Z    [    \    ]    ^    _
        .db 0xEC,0xCE,0x24,0xD6,0x74,0x7A,0x32,0xB2,0x6E,0x5e,0xBC,0xF0,0x42,0x9A,0xC8,0x10
; 6.        `    a    b    c    d    e    f    g    h    i    j    k    l    m    n    o
; 7.        p    q    r    s    t    u    v    w    x    y    z    {    |    }    ~    DEL