not sure if this is the correct place for this question but can anyone tell me the electrical characteristics of the serial input? The LCD boots fine but I am not sure of the serial input voltage polarity / level or baud rate. Its sure not compatible to PICAXE 08M serial output. Using Windows XP Hyperterminal no hardware control, I tried 5 volt TTL at 110 to 9600 baud with zero change in display while watching the serial data line change on my DVM.
Any help appreciated. Billacj
I believe that the serial LCD pack boot ups (unless changed) at 9600 baud 8-N-1 at TTL levels. It should be compatible with the PICAXE, but you might probably will have to use the inverted signal N9600 instead of 9600 or T9600.
Yes, since my first post I see TTL is inverted from the output of the Lenovo COM port which looks like -5 / + 5 and works fine with the PICAXE 08 and 18 programming.
Sooo, 9600 is the problem, the 08M chip is 2400 baud max and the 18X chip is 4800 max and it doesn’t look possible to change the 18X which is why I have to use Hyperterm at 9600 to send the 127 and Control-K characters to the Serial LCD to preprogram it to 2400 baud default.
Maybe someone else knows and in the mean time I’m working on a circuit to invert the laptop output for zero to plus 5 volts serial.
SparkFun only says 9600 TTL serial. Thanks … javascript:emoticon(‘:)’)
riden:
I believe that the serial LCD pack boot ups (unless changed) at 9600 baud 8-N-1 at TTL levels. It should be compatible with the PICAXE, but you might probably will have to use the inverted signal N9600 instead of 9600 or T9600.
I found a Max232 in my junk box and wired it up from Lenovo COM1 to the MAX232 to the SErial LCD input running Hyperterm at 9600 baud, 8 bits, 1 stop bit, no parity. Sent a | character and control K for 2400 then changed the terminal program to 2400 baud and it works fine.
Attached the Port zero serial output to the MAX232 input , out to the LCd and its fine.
Removed the MAX232.
Changed my PICAXE 08M programming serout from N to T T=TTL inverted while N=Normal RS232 right side up (?) …
All is fine. Cursor control works , happy camper now. 2400 baud is now the default speed for the LCD.
I mentioned how unreliable the serial lcd is when using t2400 output (after using t9600 to program . I have found out that using a MAX232 between the PICAXE 08M running N2400 to the MAX chip which is outputting TTL (Tmode) to the Serial LCD works best but not perfect when toggling the power on and off when developing , etc.
I figure this is either noise or start bit problem so before powering up the PICAXE I remove the Serial LCD input jumper then power off.
Before power up, the serial lcd input jumper is first attached to +5 through a 10k resistor, PICAXE power applied, wait for the LCD splash screen then move the serial lcd input jumper to the MAX chip which is connected to the serout 0 PIXAXE08 pin. Clumsy but the serial LCD has not failed yet.
In Summary, the serial LCD input must be +5 before attaching to the serial out (t2400) of the PIC or (N2400) if using the output through a MAX232.
Something is wrong with the LCD firmware. Eventually I’ll try 4800 on the PICAXE18x and 9600 with a 2X 18x Clock.
Billacj