Functional Description
1382
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
LCD Controller
the Raster Controller (clearing the LCDEN bit in LCD Raster Control (LCDRASTRCTL) register).
•
Palette loaded: This interrupt can be generated when the palette is loaded into the memory by the
DMA engine. At the same time, the PALLOAD bit in the LCD Interrupt Raw Status and Set Register
(LCDRISSET) register is set. In data-only (PALMODE = 0x2) and palette-plus-data (PALMODE = 0x0)
modes, writing 0 to this bit clears the interrupt. In the palette-only (PALMODE = 0x1) mode, this bit is
cleared by disabling the Raster Controller (clearing the LCDEN bit in the LCD Raster Control
(LCDRASTRCTL) register).
•
AC bias transition: If the ACBI field in the LCD Raster Timing 2 (LCDRASTRTIM2) register is
programmed with a nonzero value, an internal counter is loaded with this value and starts to
decrement each time LCDAC (AC-bias signal) switches its state. When the counter reaches zero, the
ACBS bit in the LCD Interrupt Raw Status and Set Register (LCDRISSET) register is set, which
delivers an interrupt signal to the system interrupt controller (if the interrupt is enabled.) The counter
reloads the value in ACBI field, but does not start to decrement until the ABC bit is cleared by writing 0
to this bit.
•
Frame transfer completed: When one frame of data is transferred completely, the DONE bit in the LCD
Interrupt Raw Status and Set Register (LCDRISSET) register is set. This bit is cleared by disabling the
Raster Controller (clearing the LCDEN bit in LCD Raster Control (LCDRASTRCTL) register). The
EOF0 and EOF1 bits in LCD Interrupt Raw Status and Set Register (LCDRISSET) register are set
accordingly.
The function enable bits are in the in LCD Raster Control (LCDRASTRCTL) register and must be set to
generate an interrupt to the CPU.
20.3.3 LIDD Bus Operation
The integrated LIDD controller has programmable timing parameters that support a wide variety of
character-based LCD panels. Alternatively, the DMA module can mimic the CPU and perform a sequence
of write-only data bus transactions to the character-based LCD panel.
LIDD mode is enabled by clearing the LCDMODE bit in the LCD Control (LCDCTL) register.
LIDD Controller operation is summarized as follows:
•
During initialization, the LCD LIDD CS0 Configuration (LIDDCS0CFG) and LCD LIDD CS1
Configuration (LIDDCS1CFG) registers are configured to match the requirements of the LCD panel
being used.
•
During normal operation, the CPU writes display data to the LIDD CS0 Data Read/Write Initiation
(LIDDCS0DATA) and LIDD CS1 Data Read/Write Initiation (LIDDCS1DATA) registers. The LIDD
interface converts the CPU write into the proper signal transition sequence for the display, as
programmed earlier. Note that the first CPU write should send the beginning address of the update to
the LCD panel and the subsequent writes update data at display locations starting from the first
address and continuing sequentially. Note that DMA may be used instead of the CPU.
•
The LIDD controller can also back status or data from the LCD panel, if the latter has this capability.
This is set up and activated in a similar manner to the write function.
describes how the signals are used to interface to external LCD modules, which are configured
by the LCDLIDDCTL register.
Table 20-1. LIDD I/O Name Map
Display Type
Interface
Type
Data Bits
LCDLIDDCTL
[2:0]
Signal Name
LCD Display
I/O Name
LCD Display I/O Description
Character Display
HD44780
Type
4
0x4
LCDDATA[7:4]
DATA[7:4]
LCD data bus (length defined
by instruction)
LCDAC
E (or E0)
Enable strobe (first display)
LCDLP
R/W
Read/Write
LCDFP
RS
Register select (data/not
instruction)
LCDMCLK
E1
Enable strobe (second display
optional)