System Architecture—IP2022 User’s Manual 54 www.ubicom.com 2.6.3 Register States Following Reset The effect of different reset sources on a register depends on the
register  and  the  type  of  reset  operation.  Some  registers  are
initialized to specific values, some are left unchanged, and some
have undefined reset states. A register that starts with an undefined state should be initialized
by the software to a known value. Do not simply test the initial
state and rely on it starting in that state consistently. Table 2-5 lists
the IP2022 registers and shows the state of each register upon
reset, with a different column for each type of reset. See Table C-
1 and Table C-2 for more detailed information. Table 2-5  Register States Following Reset Register Power-On      RST
Asserted Brown-Out Voltage   Watchdog
Timer Over- flow PCH 0xFF 0xFF 0xFF 0xFF PCL 0xF0 0xF0 0xF0 0xF0 CALLH 0xFF 0xFF 0xFF 0xFF CALLL 0xFF 0xFF 0xFF 0xFF STATUS Bits 7:5 - 111
Bits 4:3 - 00
Bits 2:0 - 000 Bits 7:5 - 111
Bits 4:3 - 00
Bits 2:0 - 000 Bits 7:5 - 111
Bits 4:3 - 01
Bits 2:0 - 000 Bits 7:5 - 111
Bits 4:3 - 10
Bits 2:0 - 000 SPDREG 0x93 0x93 0x93 0x93 XCFG 0x01* 0x01* 0x01* 0x01* Global registers    Undefined Unchanged Undefined Unchanged