Friday, 21 March 2014

Sparkfun Bus Pirate issues?

A few years ago I bought a Bus Pirate module from Seedstudio to investigate some I2C chips I had in the junkbox. Unfortunately I left it in England but last week I remembered a local emporium stocked them so I went to get one. Their version was by Sparkfun. At first glance it looked the same so I bought one and brought it home.

I found the LCD display that was giving me trouble. It was marked "emerging display EC16100TR" and was a 16x1 LCD. I still had the Seedstudio Bus Pirate LCD interface board so I connected that to the Bus Pirate. Nothing. Then I saw online that the LCD needed at least 5.4 code, mine had 5.1. So using these instructions I  upgraded it to 6.1 through the USB port. Still nothing, not even the power LED on the LCD board Lit up. As someone at BTRL once said "99% of all problems are power supply related" I started measuring voltages. I spotted that the voltage on a pin on the Bus Pirate did not correspond to those on the same pin on the LCD. I suspected the jumper cable was made badly, so I dug out another cable from my collection and the power LED lit up, progress! After some experimentation It turns out that even though It is a one line display the one line uses memory locations starting at 0 and 40 (a location usually only encountered in multiline displays) as can be demonstrated by the following Bus pirate command sequence (starting at bus pirate switch on):-

HiZ>i                                               <command
Bus Pirate v3.a                                 <response
Firmware v6.1 r1676  Bootloader v4.4
DEVID:0x0447 REVID:0x3046 (24FJ64GA002 B8)
1. HiZ
2. 1-WIRE
4. I2C
5. SPI
6. 2WIRE
7. 3WIRE
8. LCD
x. exit(without change)

This mode requires an adapter
Display lines:
 1. 1
 2. Multiple

LCD>(4) 0
WRITE: "hello"
LCD>(4) 40
WRITE: "radio"

The result on the LCD is as follows:-

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