Table 2-22. Sample Entries For Control Bank; Control Bank Registers - Sharp LH79524 User Manual

Analog-to-Digital Converter/Brownout Detector

2.2.2.10 Control Bank Registers

The Control Bank is a set of 32 16-bit registers. The contents of the registers controls the
switches for the ADC. These registers are typically configured once at startup, dictated by
the physical system. HWCTRLBx and LWCTRLBx are used together and follow the format
of the HW and LW Registers (see Section 2.2.2.1 and Section 2.2.2.2).
HWCTRLB0 (Tag 0b0000 of the High Word Control Bank) contains 16 bits of data for the
4WX (4 wire touch screen, X direction) conversion. The remaining 14 bits of data for the
4WX conversion is in LWCTRLB0 (Tag number 0b0000 of the Low Word Control Bank).
Bits 15 and 14 of the low words are reserved and read as zero. The same logic is used
for 4WY (4 wire touch screen, Y direction).
The same logic is used for the Control Bank Registers HWCBx and LWCBx. The High
Word Registers should contain:
• The settling time
• The In+ bits
• The In- bits
• The Ref+ bits.
The Low Word Registers should contain:
• The bias control settings
• The Ref- bits.
At the end of any given conversion, a 4-digit Tag Number is stored in the FIFO along with
the corresponding 10-bit output of the ADC.
For internal access into the control bank, the data writes to the registers from the APB
data bus. Each entry is a 16-bit register, with its own address space. Table 2-22 shows
sample entries for the Control Bank. More details, and examples can be found in SHARP's
Application Note 'Using the Sharp ADC with Resistive Touch Screens', available at
http://www.sharpsma.com.
TAG TYPE
4WX
4WY
4WX
4WY
2-22

Table 2-22. Sample Entries for Control Bank

TAG NAME
HWCBx0
HWCBx1
HWCBx2...HWCBx15
LWCBx0
LWCBx1
Version 1.0
LH79524/LH79525 User's Guide
CONTENTS
Settling Time[15:7] In+ [6:3]
Settling Time[15:7] In+ [6:3]
Bias control[13:2]
Bias Control[13:2]
In- [2] Ref+ [1:0]
In- [2] Ref+ [1:0]
Ref- [1:0]
Ref- [1:0]