Propeller Manual

1: Introducing the Propeller Chip
Pin Descriptions
Table 1-1: Pin Descriptions
Pin Name Direction Description
P0 – P31 I/O
General purpose I/O Port A. Can source/sink 40 mA each at 3.3 VDC.
Logic threshold is  ½ VDD; 1.65 VDC @ 3.3 VDC.
The pins shown below have a special purpose upon power-up/reset but are
general purpose I/O afterwards.
P28 - I2C SCL connection to optional, external EEPROM.
P29 - I2C SDA connection to optional, external EEPROM.
P30 - Serial Tx to host.
P31 - Serial Rx from host.
VDD --- 3.3 volt power (2.7 – 3.3 VDC).
VSS --- Ground.
BOEn I
Brown Out Enable (active low). Must be connected to either VDD or VSS.
If low, RESn becomes a weak output (delivering VDD through 5 K) for
monitoring purposes but can still be driven low to cause reset. If high,
RESn is CMOS input with Schmitt Trigger.
RESn I/O
Reset (active low). When low, resets the Propeller chip: all cogs disabled
and I/O pins floating. Propeller restarts 50 ms after RESn transitions from
low to high.
XI I
Crystal Input. Can be connected to output of crystal/oscillator pack (with
XO left disconnected), or to one leg of crystal (with XO connected to other
leg of crystal or resonator) depending on CLK Register settings. No
external resistors or capacitors are required.
XO O
Crystal Output. Provides feedback for an external crystal, or may be left
disconnected depending on CLK Register settings. No external resistors
or capacitors are required.
The Propeller (P8X32A) has 32 I/O pins (Port A, pins P0 through P31). Four of these I/O
pins, P28-P31 have a special purpose upon power-up/reset. At power-up/reset, pins P30 and
P31 communicate with a host for programming and P28 and P29 interface to an external 32
KB EEPROM (24LC256).
Propeller Manual v1.1 · Page 15