ST7735R
V0.2 30 2009-08-05
9.3 6800-series MCU parallel interface (P68 = ‘1’)
The MCU uses one of following interface: 11-lines with 8-data parallel interface, 12-lines with 9-data parallel interface,
19-lines with 16-data parallel interface, or 21-lines with 18-data parallel interface. The chip-select CSX(active low) enables
and disables the parallel interface. RESX (active low) is an external reset signal. The R/WX is the Read/Write flag and
D[17:0] is parallel data bus.
The LCD driver reads the data at the falling edge of E signal when R/WX= ‘1’ and Writes the data at the falling of the E
signal when R/WX=’0’. The D/CX is the data/command flag. When D/CX=’1’, D[17:0] bits are display RAM data or
command parameters. When D/C= ‘0’, D[17:0] bits are commands.
The 6800-series bi-directional interface can be used for communication between the micro controller and LCD driver. The
selection of this interface is done when P68 pin is high state (VDDI). Interface bus width can be selected with IM2, IM1 and
IM0.The interface functions of 6800-series parallel interface are given in Table 8.1.1.
P68
IM2
IM1
IM0
Interface D/CX
R/WX
E Function
0 0 ↓ Write 8-bit command (D7 to D0)
1 0 ↓ Write 8-bit display data or 8-bit parameter (D7 to D0)
1 1 ↓ Read 8-bit Display data (D7 to D0)
1 1 0 0 8-bit Parallel
1 1 ↓ Read 8-bit parameter or status (D7 to D0)
0 0 ↓ Write 8-bit command (D7 to D0)
1 0 ↓ Write 16-bit display data or 8-bit parameter (D15 to D0)
1 1 ↓ Read 16-bit Display data (D15 to D0)
1 1 0 1 16-bit Parallel
1 1 ↓ Read 8-bit parameter or status (D7 to D0)
0 0 ↓ Write 8-bit command (D7 to D0)
1 0 ↓ Write 9-bit display data or 8-bit parameter (D8 to D0)
1 1 ↓ Read 9-bit Display data (D8 to D0)
1 1 1 0 9-bit Parallel
1 1 ↓ Read 8-bit parameter or status (D7 to D0)
0 0 ↓ Write 8-bit command (D7 to D0)
1 0 ↓ Write 18-bit display data or 8-bit parameter (D17 to D0)
1 1 ↓ Read 18-bit Display data (D17 to D0)
1 1 1 1 18-bit Parallel
1 1 ↓ Read 8-bit parameter or status (D7 to D0)
Table 9.3.1 The function of 6800-series parallel interface
Note: applied for command code: DAh, DBh, DCh, 04h, 09h, 0Ah, 0Bh, 0Ch, 0Dh, 0Eh, 0Fh.
9.3.1 Write cycle sequence
The write cycle means that the host writes information (command or/and data) to the display via the interface. Each write
cycle (E low-high-low sequence) consists of 3 control signals (D/CX, E, R/WX) and data signals (D[17:0]). D/CX bit is a
control signal, which tells if the data is a command or a data. The data signals are the command if the control signal is low
(=’0’) and vice versa it is data (=’1’).
Figure 9.3.1 6800-Series Write Protocol
Note: E is an unsynchronized signal (It can be stopped)
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