User`s manual

28 RabbitCore RCM3200
Notes
1. When using pins 33–34 on header J1 to drive LEDs, you must use an external buffer to
drive these external LEDs. These pins are not connected on the RCM3220, which does
not have the LEDs installed.
2. The VRAM voltage is temperature-dependent. If the VRAM voltage drops below about
1.2 V to 1.5 V, the contents of the battery-backed SRAM may be lost. If VRAM drops
below 1.0 V, the 32 kHz oscillator could stop running. Pay careful attention to this volt-
age if you draw any current from this pin.
Locations R45, R46, R53, R57, and R74 allow the population of 0 Ω resistors (jumpers)
that will be used to enable future options. These locations are currently unused.
Header J2
20 PG7 Input/Output RXE
Serial Port E
21 PG6 Input/Output TXE
22 PG5 Input/Output RCLKE Serial Clock E input
23 PG4 Input/Output TCLKE Serial Clock E ouput
24 /IOWR Output External write strobe
25 /IORD Output External read strobe
26–27
SMODE0,
SMODE1
(0,0)—start executing at address zero
(0,1)—cold boot from slave port
(1,0)—cold boot from clocked Serial Port A
SMODE0 =1, SMODE1 = 1
Cold boot from asynchronous Serial Port A at
2400 bps (programming cable connected)
Also connected to
programming cable
28 /RESET_IN Input Input to Reset Generator
29 VRAM Output See Notes below table
30 VBAT_EXT 3 V battery Input
Minimum battery
voltage 2.85 V
31 +3.3V Input 3.15–3.45 V DC
32 GND
33 n.c. Reserved for future use
34 GND
Table 2. RCM3200 Pinout Configurations (continued)
Pin Pin Name Default Use Alternate Use Notes