12
SWRS224A – FEBRUARY 2019 – REVISED AUGUST 2019
Product Folder Links:
Terminal Configuration and Functions
Copyright © 2019, Texas Instruments Incorporated
4.2
Pin Attributes and Pin Multiplexing
The module makes extensive use of pin multiplexing to accommodate the large number of peripheral
functions in the smallest possible package. To achieve this configuration, pin multiplexing is controlled
using a combination of hardware configuration (at module reset) and register control.
The board and software designers are responsible for the proper pin multiplexing configuration. Hardware
does not ensure that the proper pin multiplexing options are selected for the peripherals or interface mode
used.
and
describes the general pin attributes and presents an overview of pin
multiplexing. All pin multiplexing options are configurable using the pin MUX registers. The following
special considerations apply:
•
All I/Os support drive strengths of 2, 4, and 6 mA. Drive strength is individually configurable for each
pin.
•
All I/Os support 10-
μ
A pullup and pulldown resistors.
•
By default, all I/Os float in the Hibernate state. However, the default state can be changed by SW.
•
All digital I/Os are non fail-safe.
NOTE
If an external device drives a positive voltage to the signal pads and the CC3235MODx
module is not powered, DC is drawn from the other device. If the drive strength of the
external device is adequate, an unintentional wakeup and boot of the CC3235MODx module
can occur. To prevent current draw, TI recommends any one of the following conditions:
•
All devices interfaced to the CC3235MODx module must be powered from the same
power rail as the chip.
•
Use level shifters between the device and any external devices fed from other
independent rails.
•
The nRESET pin of the CC3235MODx module must be held low until the VBAT supply to
the module is driven and stable.
•
All GPIO pins default to high impedance unless programmed by the MCU. The
bootloader sets the TDI, TDO, TCK, TMS, and Flash_SPI pins to mode 1. All the other
pins are left in the Hi-Z state.
The ADC inputs are tolerant up to 1.8 V (see
for more details about the usable
range of the ADC). On the other hand, the digital pads can tolerate up to 3.6 V. Hence, take
care to prevent accidental damage to the ADC inputs. TI recommends first disabling the
output buffers of the digital I/Os corresponding to the desired ADC channel (that is,
converted to Hi-Z state), and thereafter disabling the respective pass switches (S7 [Pin 47],
S8 [Pin 48], S9 [Pin 49], and S10 [Pin 50]). For more information, see
.
lists the pin descriptions of the CC3235MODx module.