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Topics - alk

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Character LCDs / 2x NHD-0420D3Z I2C Problem
« on: July 10, 2016, 06:01:42 PM »

I've used these displays in the past with success, and now I'm using two of them in parallel on the I2C bus and I can't figure out what's wrong. Each of the two displays has been assigned its own I2C address and they both work great if they are individually plugged in. However, when I plug them both in neither screen accepts any command and nothing is displayed. I've checked the waveforms on my scope and they are identical to the waveforms of the individual LCD operations. Therefore, I must conclude that neither slave device is holding any of the lines low. I've tried reducing my clock speeds down to well below 100kHz with no effect... I am completely at a loss as to how to debug this or where the problem even lies. Has anyone experienced this problem before or have any insight?

Character LCDs / Changing the Slave Address with NHD-0420D3Z
« on: January 09, 2015, 02:48:15 PM »
Hello, I am working on a project in which I run two of the specified character LCD displays on a single I2C bus as slaves. The master/controller in this scenario is a KL25z Freedom Platform. I've been able to successfully write text to the LCD, move the cursor around, and execute several of the commands specified in the data sheet. However, in order for my project to work, I need to be able to talk to one LCD and not the other. Obviously, I should just change the I2C slave address of one of the two LCDs. However, when I execute the command specified in the data sheet, nothing happens and the display still responds to the default address. Has anyone had this issue or know what might be wrong?

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