Digital I/O: BoosterPack Peripherals
As you may have noticed, if you have the port/pin mapping of a peripheral, you can essentially configure its GPIO and start using the peripheral. This principle extends to peripherals that are not already on the Launchpad, such as the numerous peripherals attached to the BoosterPack.
The BoosterPack is connected to the Launchpad through jumper headers. These headers are the four columns of pins on the Launchpad that connect to the black sockets underneath the BoosterPack. Each of the jumper header pins corresponds to a GPIO port/pin mapping. Additionally, all of the BoosterPack’s peripherals are mapped to a jumper header. Thus, by transitivity, each of the BoosterPack’s peripherals is mapped to some GPIO port and pin. As seen in the figure below, the jumper headers are organized into four columns (J1 through J4). The pins are also enumerated, 1 through 40, but the numbers are completely independent of the columns. So J1.1 exists, but not J2.1. The columns are simply a matter of organization.
The BoosterPack has a plethora of peripherals to work with, but we will focus on three in particular: the two push-buttons and the RGB LED. Just like on the Launchpad, these peripherals function as they imply, with the RGB LED having three separate connections for each of its colors.
Let us determine which jumper headers each of these peripherals are connected to. The top section “A closer look at your new BoosterPack Plug-in Module” labels the connections next to each peripheral. Alternatively, the bottom section “Pinout Diagram for your BoosterPack” displays each of the jumper header connections in greater detail. In either case, the two buttons are mapped to J4.32 and J4.33, and the colors of the RGB LED are mapped to J4.37, J4.38, and J4.39. If you have good eyesight, you should also find the same information on the board itself!
The above figure shows how each of the jumper headers are connected to the GPIO pins on the Launchpad. If we match the jumper header connections from the BoosterPack to the Launchpad, we can determine the GPIO port/pin mappings of each of the BoosterPack peripherals. For instance, we know Button 1 on the BoosterPack is mapped to J4.33. If we look at the Launchpad Quick Guide (which contains the figure above) and look at J4.33, we can see that the jumper header is mapped to Port 5, Pin 1. Thus, Button 1 on the BoosterPack is mapped to P5.1.
Now that we have the GPIO mappings, we can configure the respective pins to make use of the BoosterPack peripherals. However, we need to figure out if the push buttons need pull resistors or not. The question for you is what document do we need to look into to get our answer.