Newhaven Display Forum

Newhaven Products => Character LCDs => Topic started by: joestaudt on May 04, 2015, 08:29:15 AM

Title: NHD-C0216CZ-FSW-FBW Serial Interface RS line question
Post by: joestaudt on May 04, 2015, 08:29:15 AM
I have a question about the use of the RS line for the serial interface, and about writing data in general.

First, can I send multiple bytes of data following a command to set the DDRAM address, or must I send command, data byte, command, data byte, command, data byte, etc.

Second, if I can send multiple data bytes following a single command, do I need to pulse the RS line for each data byte, or do I only need to pulse it for the first data byte?
Title: Re: NHD-C0216CZ-FSW-FBW Serial Interface RS line question
Post by: Michael_L on May 05, 2015, 09:56:26 AM
You can send multiple bytes of data following a command to set the DDRAM address, as the address counter will increment automatically.  The RS line doesn't need to be pulsed, it is an indicator for the display's controller to interpret the byte being sent as either a command or data (Command: RS = Low | Data: RS = High).  So, if you were to send 8 bytes of data for example, you would only need to bring RS high before the first data write, and proceed to write the 7 remaining bytes while RS is still high.
Title: Re: NHD-C0216CZ-FSW-FBW Serial Interface RS line question
Post by: joestaudt on May 05, 2015, 12:19:19 PM
Michael,

Thanks for the clarification. The timing diagrams in the spec showed RS as a pulse, and there is nothing that shows or describes a multiple-data transfer. It was rather confusing.

Joe
Title: Re: NHD-C0216CZ-FSW-FBW Serial Interface RS line question
Post by: joestaudt on May 05, 2015, 01:16:31 PM
Michael,

A quick (I hope) follow-on question. Each instruction takes a certain amount of time to complete (26.3 usec for most, with a 380kHz clock). When I write to DDRAM, do I have to delay that amount of time between the address instruction and the first write instruction, and then after each write instruction? Or can all the data words be sent with no delay between?

Also, back on the RS signal, the timing diagram shows RS going active with the last bit of the previous word. Does it have to go active (and inactive?) that far ahead, or can it go active on the same (falling) clock edge as the first bit of the data word and inactive after the last bit?

Joe
Title: Re: NHD-C0216CZ-FSW-FBW Serial Interface RS line question
Post by: Michael_L on May 11, 2015, 09:34:29 AM
The execution time applies to each type of data transfer as indicated in the datasheet's command table on page 6.  After each transfer, the execution shown should be allowed for before sending another byte of data.

The timing for the RS is shown in the timing diagram / table in the datasheet.  These timing requirements are what need to be met for the display's proper use.  Therefore, anything you are trying to do that violates these requirements will not guarantee reliable operation.