PSoC3 can be divided into analog and digital internals. The analog part includes Delta-Sigma ADC, operational amplifier, comparator, DAC and SC/CT module. Digital parts include, for example, CPU, RAM, ROM, DMA, UDBs, clocks, and the like.
The analog global bus (AGs) and the analog multiplex bus (AMUXBUS) provide a connection between the GPIO and the internal analog module. As shown in Figure 1, a total of 16 AGs in PSoC3 are distributed in four quadrants, each quadrant includes 4 AGs bus (AGR[7:4], AGR[3:0], AGL[7:4], and AGL[3:0]); AMUXBUS can be used between any GPIO and most analog module inputs and outputs connection. In this way, AGs and AMUXBUS provide up to 18 signal connections between the GPIO and the analog module.
For the interconnection between internal analog modules, PSoC3 is implemented by analog local bus (ABUS). There are 8 ABUS buses, 4 ABUSL[3:0] are located on the left side of the chip, and 4 ABUSR[3:0] are located on the chip. right.
There are also about 20 dedicated channels between the GPIO and the analog blocks. These dedicated channels provide low-impedance connections, such as the IDAC and op amp Opamp in PSoC3, which is described later in Part 3.
Figure 1. PSoC3 internal analog/digital distribution
2, PSoC3 analog wiring examples
PSoC Creator, a software tool from Cypress, provides analog cabling to the user. Of course, users can manually route analog devices to select better pins and better traces. The following is a design example.
If the signal is required to be input from P4[0] and P4[1], amplified by PGA1 and PGA2, and then connected to the differential input of the ADC to acquire the signal, the schematic diagram designed in PSoC Creator is shown in Figure 2 below:
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