003-UART-1602

003-UART-1602

UART/RS232 Enabled controller for a basic 1602 Monochrome LCD, in 4-bit mode using the CH32V003 - TSSOP-20 MCU
Features:

• Selectable Baudrate
• Backlight Control using UART or Hardware override
• 4-bit LCD Control protocol support
• Automatic Line Scroll
• Operation down to 2.7v
• LCD Contrast Charge Pump
• Advance Display Control over UART

Display Operation

The display will read any incoming UART or RS232 Data and print it to the screen in realtime - If the edge of the screen is exceeded, the display will drop incoming data.
When Line Feed is received, and the Display is already on Line 2, the display will Scroll Down, so the line being printed to remains as Line 2

See Control Characters for a list of control commands that can be used for the display

Startup Conditions

When the Display is powered on, and before it receives any UART data, the device is in the following state:

• LCB Backlight OFF
• Display Configured and blanked

Selectable Baudrate

Receiver Baudrate is selected via the DIP-Switches onboard.
The setting is checked once a second so the setting can be changed on the fly.

B1 B0  Baud
0  0   4800
0  1   9600
1  0   115200
1  1   460800

Low Voltage Operation

There is a negative charge pump onboard that provides a near-rail negative voltage, that is fed to one end of the contrast selection Potentiometer.
These LCDs are only officially rated at 5v, so use lower voltages AT YOUR OWN RISK.
To disable the charge pump, do not populate the components, and short the JMP_V0 Jumper.
The Minimum Voltage for the unit is 2.7v

Control Characters

BELL 0x07 - Flashes the Backlight quickly for 3 Seconds
LF 0x0A - Feeds line down, keeping Column Position
CR 0x0D - Returns to the First Column on the current line
DC1 0x11 - Device Control 1, Turns Backlight On
DC2 0x12 - Device Control 2, Turns Backlight Off
DC3 0x13 -
DC4 0x14 -
ESCAPE 0x1B - Clears the Screen and returns to position 0,0

Any Control Characters not mentioned above will be ignored.

Pinout

PA1  Baud Select 1
PA2  Baud Select 2

PC0  ---
PC1  LCD_RS  Register Select
PC2  LCD_RW  Read/Write
PC3  LCD_EN  Enable
PC4  LCD_D4  Display Data Pin 4
PC5  LCD_D5  Display Data Pin 5
PC6  LCD_D6  Display Data Pin 6
PC7  LCD_D7  Display Data Pin 7

PD0  Backlight Control
PD1  !!Reserved for SWIO!!
PD2  --
PD3  --
PD4  Charge Pump PWM
PD5  TX  UART Transmit (Not Connected)
PD6  RX  UART Receive
PD7  Reserved for NRST

MkII PCB Partslist

C1    0603 1uF 10V
C2    0603 1uF 10V
C3    0603 1uF 10V
R1    0603 4K7
R2    100K 5mm x 5mm Potentiometer
D1    BAT54S
Q1    AO3401 P-Ch
Q2    A03400 N-Ch
U1    CH32V003
SW1   1.27mm 2P DIP Switch

TODO

• Device Contol 3 and 4 Behaviour

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