Post by tc275project1 on Apr 9, 2018 21:13:57 GMT
After looking through the data sheets i discovered that some of the pins appear to be connected to more than one pin on the tc275 chip. How is this possible?
The parts highlighted in bold are my concerns as this seems to indicate that analog pin 4,5,12,13,14,15 are connected to both a digital pin (PX e.g. P20.7) and an analog pin (SARX e.g. SAR5.6). Can someone please explain this either with a schematic or words please?
Also what is A step and B step and what is the purpose of having these?
Analog pin 4 ADCL.5 SAR3.0/P10.7
Analog pin 5 ADCL.6 SAR3.1/P10.8
Analog pin 6 ADCL.7 SAR2.5
Analog pin 7 ADCL.8 SAR2.4
Analog pin 8 ADCH.1 SAR0.3
Analog pin 9 ADCH.2 SAR0.2
Analog pin 10 ADCH.3 SAR0.1
Analog pin 11 ADCH.4 SAR0.0
Analog pin 12/DAC0 ADCH.5 SAR5.4/P20.9/P33.10
Analog pin 13/DAC1 ADCH.6 SAR5.5/P33.11
Analog pin 14/CAN RX ADCH.7 SAR5.6/P20.7 CAN0 RX
Analog pin 15/CAN TX ADCH.8 SAR5.7/P20.8 CAN0 TX
Digital pin 48 XIO.29 P21.3 (B-step) P21.1 (A-step) via link
Digital pin 49 XIO.30 P21.0
Digital pin 50 (MISO) XIO.31 P33.4 + P21.3
Digital pin 51 (MOSI) XIO.32 P2.8 + P13.3
Digital pin 52 (SCK) XIO.33 P33.5 + P15.8
Digital pin 53 (SS) XIO.34 P11.12 + P20.10
Post by Admin on Apr 10, 2018 8:12:49 GMT
The TC275 has far more pins that the Arduino Mega form factor provides so to make as many TC275 peripherals accessible we have sometimes got multiple CPU pins going to one Arduino pin. Using the ShieldBuddy Arduino add-in, no pin contentions should occur as we have taken care of this. The analog pins are a special case. The Arduino Mega's ADC pins can also be used as general purpose IO. Some shields like the RAMPS 3D printer boards use analog pins as GPIO. The TC275's ADC pins can only be used for analog inputs. This is mainly to improve ADC performance. To get around this, the ShieldBuddy takes spare normal GPIO pins to the Arduino analog pins. However in the ShieldBuddy startup these GPIO pins are set into input with no pull device mode so that they do not cause any strange offsets on the analog voltage readings.
All ShieldBuddies use B-step or later Tc275 silicon. In fact most are CA-step.