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Updated readme for ports/atmega328

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This commit is contained in:
Steve Karg
2025-03-13 17:17:38 -05:00
parent 4df896b820
commit d7858c0b3a
1 changed files with 28 additions and 27 deletions
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ports/atmega328/README.md
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@@ -4,7 +4,7 @@ The Arduino Uno R3 platform for this example uses the following peripherals:
1) USB bootloader using AVR-119 protocol
2) 7-position DIP switch for MS/TP MAC address
2) Arduino Uno V3 I/O to BACnet Objects map - see below
3) Arduino Uno V3 compatible RS485 shield (DFR0259)
@@ -21,10 +21,10 @@ The Arduino Uno R3 platform for this example uses the following peripherals:
| GND | GND | GND | |
| VIN | VIN | | |
| | | | |
| ADC0/PC0 | A0 | | AV 0 Millivolts |
| ADC1/PC1 | A1 | | AV 1 Millivolts |
| ADC2/PC2 | A2 | | AV 2 Millivolts |
| ADC3/PC3 | A3 | | AV 3 Millivolts |
| ADC0/PC0 | A0 | | AV-0 Millivolts |
| ADC1/PC1 | A1 | | AV-1 Millivolts |
| ADC2/PC2 | A2 | | AV-2 Millivolts |
| ADC3/PC3 | A3 | | AV-3 Millivolts |
| ADC4/PC4 | A4* | | |
| ADC5/PC5 | A5* | | |
| | | | |
@@ -32,18 +32,18 @@ The Arduino Uno R3 platform for this example uses the following peripherals:
| ADC4/PC4 | SDA* | I2C | |
| AVDD | AREF | | |
| GND | GND | | |
| SCK/PB5 | D13 | LED-L ANODE (+)| BV 99 (output) |
| MISO/PB4 | D12 | | BV 9 (output) |
| MOSI/PB3 | D11 | | BV 8 (output) |
| SS/PB2 | D10 | | BV 7 (output) |
| OC1/PB1 | D9 | | BV 6 (output) |
| ICP/PB0 | D8 | | BV 5 (output) |
| SCK/PB5 | D13 | LED-L ANODE (+)| BV-99 (output) |
| MISO/PB4 | D12 | | BV-9 (output) |
| MOSI/PB3 | D11 | | BV-8 (output) |
| SS/PB2 | D10 | | BV-7 (output) |
| OC1/PB1 | D9 | | BV-6 (output) |
| ICP/PB0 | D8 | | BV-5 (output) |
| | | | |
| AIN1/PD7 | D7 | | BV 4 (input) |
| AIN0/PD6 | D6 | | BV 3 (input) |
| T1/PD5 | D5 | | BV 2 (input) |
| T0/PD4 | D4 | | BV 1 (input) |
| INT1/PD3 | D3 | | BV 0 (input) |
| AIN1/PD7 | D7 | | BV-4 (input) |
| AIN0/PD6 | D6 | | BV-3 (input) |
| T1/PD5 | D5 | | BV-2 (input) |
| T0/PD4 | D4 | | BV-1 (input) |
| INT1/PD3 | D3 | | BV-0 (input) |
| INT0/PD2 | D2 | CE DE /RE RTS | RS485 |
| TXD/PD1 | D1/Tx** | TXD | RS485 |
| RXD/PD0 | D0/Rx** | RXD | RS485 |
@@ -84,24 +84,25 @@ The Makefile includes a recipe to use avrdude to program the Uno R3 via USB
make install
#### GCC and CStack Usage
#### Board diagnostics and configuration
CStack check for GCC is included in the device object as property 512.
The compile shows 352 (.bss) + 136 (.data) = 488 bytes of RAM used, and
the ATmega328 has 2048 bytes of RAM, leaving 1560 bytes for the CStack.
BACnet Device object proprietary property 512 is mapped to the CStack Size
and returns 1376 using ReadProperty request. After some ReadProperty and
WriteProperty requests, the CStack shows 1159 CStack bytes free.
Note that the value 0xC5 (197) was used to paint the CStack.
Keep this in mind when developing.
| BACnet Object | Description | Default | R/W |
|:------------------|:-----------------|:---------------|:------|
| AV-92 | Device ID | 260123 | R/W |
| AV-93 | MS/TP bitrate | 38400 bps | R/W |
| AV-94 | MS/TP MAC | 123 | R/W |
| AV-95 | MS/TP Max Manager| 127 | R/W |
| AV-96 | MCU Frequency | F_CPU | R |
| AV-97 | CStack Size | 0 | R |
| AV-98 | CStack Unused | 0 | R |
| AV-99 | Uptime | 0 | R |
##### Shield option
The DFR0259 shield for RS485 was used, but any RS485 circuit could be
attached to the Arduino Uno R3 using the same pins for Tx, Rx, CE RE/DE RTS.
A 7-position DIP switch was connected to GPIO for the MS/TP MAC address,
but the value could also be stored in EEPROM.
The MS/TP MAC address, bitrate, and max-manager are stored in EEPROM.
### BACnet Capabilities