57
Similarly, alphanumeric
LCDs also have operating frequency limit. Usually it is about 250 kHz. Refer to the datasheet of the
LCD you are using. If the digital I/Os are faster than this max limit value, it is highly likely that the LCD
won’t show any valid data at all or it will show up garbage characters. To counter this issue, either we
have to use a low MCU clock frequency or add some delays in our LCD library to slow the processes
down.
Software delays are often required to introduce time delays in a code. Such delays will be needed for
the LCD library. As discussed before by default, CCS doesn’t provide delay time functions i.e. delay
milliseconds (delay_ms) and delay micro-seconds (delay_us). Instead it provides _delay_cycles
function for delays. Most of us will not be comfortable with delay cycles function as it doesn’t directly
signify the amount of time wasted. Thus, delay time functions are musts. Although software delays
are inefficient in terms of coding and performance, they are helpful in debugging stuffs quickly in a
rudimentary fashion. A much novel and precise approach of creating time delays is achieved using a
timer. In this example, we will need both LCD and delay libraries. I already showed how to incorporate
custom libraries in a CCS Project and here I implemented that addition.
There are other types of displays in the realm of LCDs. These include monochrome graphical LCDs, TFT
LCDs, OLED LCDs, etc. However, it is literally impossible to integrate these displays with MSP430G2xx
micros. Firstly, this is so due to low memories and secondly due to low pin counts. MSP430G2xx micros
are also not as fast as ARM micros. Speed plays a vital role in processing graphics.
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