I have a GLK24064-25 display. I2C writes work fine. Just like other I2C chips I use. However, the 2 reads (READ VERSION and READ MODULE TYPE) don't work yet. The manual is not that clear. Usually, when issuing I2C reads, you first issue a WRITE of the command, then issue a RESTART, then a READ. The data is then on the bus after 1 extra read cycle. This mode doesn't work. It puts a 00 on the bus all the time. If you issue a READ first, the I2C bus doesn't recognize the next byte. I am looking at an I2C analyzer to see what bytes are going back and forth.
Anybody have the proper procedure for I2C reads with this display. I know some displays do not have the I2C read capability, but this display does according to the datasheet.
Thanks.
Sutton Mehaffey
I2C reads from display
-
Jon
- Matrix Orbital
- Posts: 231
- Joined: Mon Oct 24, 2005 10:38 am
- Location: Calgary, AB, Canada
- Contact:
Hi Sutton,
I believe I have got to you about this question over the phone, however for the benifit of everybody else reading this, the display can only return keypresses in I2C. So the 00 that you have read, just means that there are no keypresses in the buffer. If you receive a byte, that means a key was pressed, and it was in the buffer.
Sorry that the manual wasn't more clear on this.
--
jon
I believe I have got to you about this question over the phone, however for the benifit of everybody else reading this, the display can only return keypresses in I2C. So the 00 that you have read, just means that there are no keypresses in the buffer. If you receive a byte, that means a key was pressed, and it was in the buffer.
Sorry that the manual wasn't more clear on this.
--
jon
Re: I2C reads on GLK24064-25
Jon,
According to the GLK24064-25 datasheet, section 4.1.1, it does support I2C reads. It talks about the reads in the 2nd paragraph. Other displays such as the GLK12232-25 do not support I2C reads, and it is documented in the datasheet. But, I think the GLK24064-25 does support reads if you have the right version.
According to Raquel, versions 5.4 and up support these reads. I have version 5.3, which may confirm why my display reads 00. She said I have to send my display in for 'upgrade' to be able to do this.
Sutton
According to the GLK24064-25 datasheet, section 4.1.1, it does support I2C reads. It talks about the reads in the 2nd paragraph. Other displays such as the GLK12232-25 do not support I2C reads, and it is documented in the datasheet. But, I think the GLK24064-25 does support reads if you have the right version.
According to Raquel, versions 5.4 and up support these reads. I have version 5.3, which may confirm why my display reads 00. She said I have to send my display in for 'upgrade' to be able to do this.
Sutton