
SPRS094I APRIL 1999 REVISED SEPTEMBER 2003
15
POST OFFICE BOX 1443
HOUSTON, TEXAS 772511443
pin functions (continued)
Table 2. LF240x Pin List and Package Options
(Continued)
PIN NAME
LF2407
LF2406
LF2402
DESCRIPTION
ADDRESS, DATA, AND MEMORY CONTROL SIGNALS (CONTINUED)
READY
120
READY is pulled low to add wait states for external accesses. READY indicates
that an external device is prepared for a bus transaction to be completed. If the
device is not ready, it pulls the READY pin low. The processor waits one cycle
and checks READY again. Note that the processor performs READY-detection
if at least one software wait state is programmed. To meet the external READY
timings, the wait-state generator control register (WSGR) should be
programmed for at least one wait state.
(
↑
)
MP/MC
118
Microprocessor/Microcomputer mode select. If this pin is low during reset, the
device is put in microcomputer mode and program execution begins at 0000h
of internal program memory (Flash EEPROM). A high value during reset puts
the device in microprocessor mode and program execution begins at 0000h of
external program memory. This line sets the MP/MC bit (bit 2 in the SCSR2
register).
(
↓
)
Active high to enable external interface signals. If pulled low, the 2407 behaves
like the 2406/2402—i.e., it has no external memory and generates an illegal
address if DS is asserted. This pin has an internal pulldown.
ENA_144
122
(
↓
)
VIS_OE
97
Visibility output enable (active when data bus is output). This pin is active (low)
whenever the external data bus is driving as an output during visibility mode.
Can be used by external decode logic to prevent data bus contention while
running in visibility mode.
A0
80
Bit 0 of the 16-bit address bus
A1
78
Bit 1 of the 16-bit address bus
A2
74
Bit 2 of the 16-bit address bus
A3
71
Bit 3 of the 16-bit address bus
A4
68
Bit 4 of the 16-bit address bus
A5
64
Bit 5 of the 16-bit address bus
A6
61
Bit 6 of the 16-bit address bus
A7
57
Bit 7 of the 16-bit address bus
A8
53
Bit 8 of the 16-bit address bus
A9
51
Bit 9 of the 16-bit address bus
A10
48
Bit 10 of the 16-bit address bus
A11
45
Bit 11 of the 16-bit address bus
A12
43
Bit 12 of the 16-bit address bus
A13
39
Bit 13 of the 16-bit address bus
A14
34
Bit 14 of the 16-bit address bus
A15
31
Bit 15 of the 16-bit address bus
D0
127
Bit 0 of 16-bit data bus
(
↑
)
(
↑
)
D1
Bold, italicized pin names
indicate pin function after reset.
GPIO General-purpose input/output pin. All GPIOs come up as input after reset.
§It is highly recommended that VCCA be isolated from the digital supply voltage (and VSSA from digital ground) to maintain the specified accuracy
and improve the noise immunity of the ADC.
Only when all of the following conditions are met: EMU1/OFF is low, TRST is low, and EMU0 is high
#No power supply pin (VDD, VDDO, VSS, or VSSO) should be left unconnected. All power supply pins must be connected appropriately for proper
device operation.
LEGEND:
↑
Internal pullup
↓
Internal pulldown
(Typical active pullup/pulldown value is
±
16
μ
A.)
130
Bit 1 of 16-bit data bus