AR# 53104

2012.4 Vivado, AXI_TFT v1.00a – A write to the CCR register during initialization of a Chrontel device affects pending IIC transactions

Description

The AXI TFT controller supports configuration of a Chrontel CH-7310 chip through the IIC interface.

The IIC interface automatically configures the default values to the Chrontel chip immediately after reset de-assertion.

While AXI TFT is configuring the Chrontel chip, a write to the CCR register over AXI affects the already pending IIC transactions.

How can I resolve this issue?

Solution

This is a limitation of the AXI_TFT core. 

To work around this issue, the following two precautions need to be taken:

1. Wait for 10 us after reset before writing to the CCR register (BASEADDR+0x0000000C).

2. Before each write into the CCR register, ensure any previous writes to CCR have executed by polling the 31st bit for a value of 0.

This issue is fixed in Vivado 2013.3.

AR# 53104
Date 03/24/2015
Status Active
Type General Article
IP