| Location | content | Location | content | Location | content | Location | content | 
|---|---|---|---|---|---|---|---|
| 00 | Messages from EUSART1 to EUSART2  | 
    40 | 80 | EUSART2 send only  | 
    C0 | EUSART2 receive and reply  | |
| 01 | 41 | 81 | C1 | ||||
| 02 | 42 | 82 | C2 | ||||
| 03 | 43 | 83 | C3 | ||||
| 04 | 44 | 84 | C4 | ||||
| 05 | 45 | 85 | C5 | ||||
| 06 | 46 | 86 | C6 | ||||
| 07 | 47 | 87 | C7 | ||||
| 08 | 48 | 88 | C8 | ||||
| 09 | 49 | 89 | C9 | ||||
| 0A | 4A | 8A | CA | ||||
| 0B | 4B | 8B | CB | ||||
| 0C | 4C | 8C | CC | ||||
| 0D | 4D | 8D | CD | ||||
| 0E | 4E | 8E | CE | ||||
| 0F | 4F | 8F | CF | ||||
| 10 | 50 | DCC_STATE | 90 | D0 | |||
| 11 | 51 | DCC_SUBST | 91 | D1 | |||
| 12 | 52 | DCC_addr | 92 | D2 | |||
| 13 | 53 | 93 | D3 | ||||
| 14 | 54 | DCC_msg | 94 | D4 | |||
| 15 | 55 | 95 | D5 | ||||
| 16 | 56 | 96 | D6 | ||||
| 17 | 57 | DCC_areg | 97 | D7 | |||
| 18 | SO_INp0 | 58 | DCC_cksm | 98 |   | D8 | For ESP-01 WiFi total 64 bytes  | 
| 19 | SO_INp1 | 59 | DCC_pr Previous timer value  | 
    99 |   | D9 | |
| 1A | SO_INp2 | 5A | 9A |   | DA | ||
| 1B | SO_ot | 5B | DCC_inot buffer indices | 9B |   | DB | |
| 1C | SO_lim | 5C | circular buffer of pulse width measurements  | 
    9C |   | DC | |
| 1D | SI_in | 5D | 9D |   | DD | ||
| 1E | SI_cksm | 5E | 9E |   | DE | ||
| 1F | SI_size | 5F | 9F |   | DF | ||
| 20 | EUSART1 receive and reply  | 
    60 | EUSART1 send only D0, D1 6 B2 4  | 
    A0 | Messages from EUSART2 to EUSART1  | 
    E0 | |
| 21 | 61 | A1 | E1 | ||||
| 22 | 62 | A2 | E2 | ||||
| 23 | 63 | A3 | E3 | ||||
| 24 | 64 | A4 | E4 | ||||
| 25 | 65 | A5 | E5 | ||||
| 26 | 66 | A6 | E6 | ||||
| 27 | 67 | A7 | E7 | ||||
| 28 | 68 | A8 | E8 | ||||
| 29 | 69 | A9 | E9 | ||||
| 2A | 6A | AA | EA | ||||
| 2B | 6B | AB | EB | ||||
| 2C | 6C | AC | EC | ||||
| 2D | 6D | AD | ED | ||||
| 2E | 6E | AE | EE | ||||
| 2F | 6F | AF | EF | ||||
| 30 | 70 | B0 | F0 | ||||
| 31 | 71 | B1 | F1 | ||||
| 32 | 72 | B2 | F2 | ||||
| 33 | 73 | B3 | F3 | ||||
| 34 | 74 | B4 | F4 | ||||
| 35 | 75 | B5 | F5 | ||||
| 36 | 76 | B6 | F6 | ||||
| 37 | 77 | B7 | F7 | ||||
| 38 | FM_FAL FRAM address lsb | 78 | DGpw0H | B8 | EO_INp0 send from ERX_buf | F8 | |
| 39 | FM_FAH FRAM address msb | 79 | B9 | EO_INp1 send from L2E_buf | F9 | ||
| 3A | FM_RAL RAM address lsb | 7A | DGpw0L | BA | EO_INp2 send from ETX_buf | FA | |
| 3B | FM_RAH RAM address msb | 7B | BB | EO_ot | FB | ||
| 3C | FM_BC byte count | 7C | DGpw1 | BC | EO_lim | FC | |
| 3D |   | 7D | BD | EI_in | FD | ||
| 3E |   | 7E |   | BE | EI_cksm | FE | |
| 3F | ser_cfg Available interfaces | 7F |   | BF | EI_size | FF |