User manual

LPCXpresso Experiment Kit - User’s Guide

Page 82

Figure 48 – Breadboard with Shift Register and 7-segment Display, with MISO

7.12.2 Lab 11b: Control 7-segment Display

In this experiment will shall revisit Lab 8e: Control 7-segment Display via Shift Register (on page 68)

again. In that experiment the SPI bus was simulated in software. Now the SSP peripheral block shall

be used for the SPI communication. Refresh your memory of the schematic by looking at Figure 41

again. Rebuild the breadboard circuit in Figure 42 (which you should have done already in Lab 11a).

The MISO signal is no longer need since the content of the shift register is of no interest.

Use GPIO_4-LED-SSEL (PIO0_2) as SSEL signal and do not forget to initialize this GPIO signal as an

output and to also control the signal levels during SPI communication, just like in the previous Lab.

7.12.3 Lab 11c: Access SPI E2PROM

In this experiment we will interface the 25LC080 chip, which is a 1024 byte serial E2PROM that directly

interface the SPI bus. In this experiment signal GPIO_8-LED-SSEL (PIO2_0) is used as SSEL signal.

Have a look at the datasheet for the 25LC080 chip, for example here:

http://ww1.microchip.com/downloads/en/DeviceDoc/22151b.pdf or search Microchip’s website if the

link does not work.

The 25LC080 chip has a set of instructions. All SPI transmissions begin with the instruction to execute.

The needed parameters (for the instruction) are then transmitted. The set of instructions are shown in

the picture below (the picture comes from the 25LC080 datasheet).

MISO