From ffc164c25f65a74cdddb89f91101f710e6a5f778 Mon Sep 17 00:00:00 2001
From: Jake <jake.read@cba.mit.edu>
Date: Sat, 30 Dec 2023 01:23:36 -0500
Subject: [PATCH] defeat spi-oddity, transmit and rx data
---
rpi_spi/2023-12-29_pi-spi-rates.md | 4 +-
.../spi_peripheral_bare.ino | 63 +----------
rpi_spi/code/spi_peripheral_bare/spipi.cpp | 105 ++++++++++--------
rpi_spi/code/spi_peripheral_bare/spipi.h | 2 +-
4 files changed, 66 insertions(+), 108 deletions(-)
diff --git a/rpi_spi/2023-12-29_pi-spi-rates.md b/rpi_spi/2023-12-29_pi-spi-rates.md
index cc1acd0..59c5b2f 100644
--- a/rpi_spi/2023-12-29_pi-spi-rates.md
+++ b/rpi_spi/2023-12-29_pi-spi-rates.md
@@ -83,4 +83,6 @@ OK, so to see if we can get up to that 10Mbit real-transfer-rate target, I think
I have hello-worlded this with the Earle Core, but their SPI implementation is strange - since it's simple enough (I'm starting to see that... that's the pint), I'll just roll my own... listening to CS down / up interrupts to frame packets, stuffing buffers, you know the dealio. It's 730pm here but that's just time to put the embedded hardo hat on...
-I'm going a bit mad with this; I can get GPIO interrupts to fire *just on a falling edge* but not *just on a rising edge* ... I should see if I can access some lower level masks, or something? But it's genuinely sending events *marked* as *rising edge* events on falling and rising edges...
\ No newline at end of file
+I'm going a bit mad with this; I can get GPIO interrupts to fire *just on a falling edge* but not *just on a rising edge* ... I should see if I can access some lower level masks, or something? But it's genuinely sending events *marked* as *rising edge* events on falling and rising edges...
+
+There's another oddity in here... the RP2040 only uses SPI framing where the CS line is pulsed per frame (7-16 bits), so we need to handle it in software, though IDK exactly how to do this as a peripheral, though apparently [this lad](https://github.com/raspberrypi/pico-sdk/issues/88#issuecomment-1402204730) found [a workaround?](https://github.com/uwopus/pico-code/blob/3594e67c1ac34e5454eb4db8362b673bcc7c8862/opus_comms/opus_comms.c#L44-L46) which references 4.4.3.13
\ No newline at end of file
diff --git a/rpi_spi/code/spi_peripheral_bare/spi_peripheral_bare.ino b/rpi_spi/code/spi_peripheral_bare/spi_peripheral_bare.ino
index 2bdb72f..1079bb8 100644
--- a/rpi_spi/code/spi_peripheral_bare/spi_peripheral_bare.ino
+++ b/rpi_spi/code/spi_peripheral_bare/spi_peripheral_bare.ino
@@ -4,42 +4,7 @@
// using a (basically raspberry pi pico) W5500-EVB-Pico
// with earle philhower core
-#define PIN_DEBUG 1
-
-// SPI
-// SPISettings settings(1000000, MSBFIRST, SPI_MODE0);
-
-uint8_t txBuffer[1024];
-volatile uint32_t rxCount = 0;
-volatile uint32_t rxSize = 0;
-
-// fires when we get data, I presume ?
-// byte rxBuffer[1024];
-// this *is unrelated to the CS pin* but should be !
-// it actually fires basically every data chunk...
-// void onRx(uint8_t* data, size_t len){
-// // actually, for the echo we can copy
-// // directly across, non ?
-// // digitalWrite(PIN_DEBUG, HIGH);
-// // memcpy(txBuffer, data, len);
-// rxCount ++;
-// if(len > rxSize) rxSize = len;
-
-// // shifty shifty
-// // digitalWrite(PIN_DEBUG, LOW);
-// }
-
-// fires at the end of a transaction ?
-// void onTxComplete(void){
-// SPISlave1.setData((uint8_t*)txBuffer, 32);
-// digitalWrite(PIN_DEBUG, !digitalRead(PIN_DEBUG));
-// }
-
void setup(void){
- // a debug light and pin,
- pinMode(PIN_DEBUG, OUTPUT);
- digitalWrite(PIN_DEBUG, LOW);
-
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, LOW);
@@ -48,26 +13,6 @@ void setup(void){
// the spi setup
spipi_begin();
-
- // fill our demo buffer
- for(uint16_t i = 0; i < 1024; i ++){
- txBuffer[i] = i;
- }
-
- // SPISlave1.setData((uint8_t*)txBuffer, 32);
-
- // // pin config (2040 GPIO Nums)
- // SPISlave1.setCS(13);
- // SPISlave1.setSCK(10);
- // SPISlave1.setRX(12);
- // SPISlave1.setTX(11);
-
- // // callbacks
- // SPISlave1.onDataRecv(onRx);
- // SPISlave1.onDataSent(onTxComplete);
-
- // // startup
- // SPISlave1.begin(settings);
}
uint32_t lastUpdate = 0;
@@ -77,9 +22,9 @@ void loop(void){
if(lastUpdate + updateInterval < millis()){
lastUpdate = millis();
digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
- displayPrint(String(rxCount) + "\n" +
- String(rxSize) + "\n" +
- String(spipi_get_events())
- );
+ displayPrint(spipi_print());
+ // displayPrint(String(rxCount) + "\n" +
+ // String(rxSize)
+ // );
}
}
\ No newline at end of file
diff --git a/rpi_spi/code/spi_peripheral_bare/spipi.cpp b/rpi_spi/code/spi_peripheral_bare/spipi.cpp
index 0b06d2b..8dd0e27 100644
--- a/rpi_spi/code/spi_peripheral_bare/spipi.cpp
+++ b/rpi_spi/code/spi_peripheral_bare/spipi.cpp
@@ -18,8 +18,9 @@
// /jaker/AppData/Local/Arduino15/packages/rp2040/3.6.1/pico-sdk/src/ ...
// /rp2040/rp2_common/hardware_gpio/include/hardware/gpio.h
+#define PIN_DEBUG 1
-#define PIN_CS 14
+#define PIN_CS 13
#define PIN_SCK 10
#define PIN_RX 12
#define PIN_TX 11
@@ -34,79 +35,89 @@
#define SPI_IMSC_RTIM_ON (1 << 1)
#define SPI_IMSC_RORIM_ON (1)
+// some static buffs
+uint8_t rxBuffer[255];
+volatile uint8_t rxPtr = 0;
-
-volatile uint32_t event_latest = 12;
-uint32_t spipi_get_events(void){
- return event_latest;
+String spipi_print(void){
+ return String(rxBuffer[0]) + ", " + String(rxBuffer[1]);
}
+uint8_t txBuffer[255];
+volatile uint8_t txPtr = 0;
+volatile uint8_t txLen = 32;
+
// we catch rising edges to delineate packet-end
void spipi_gpio_irq_handler(uint gpio, uint32_t events){
if(gpio_get(PIN_CS)){
- gpio_put(1, !gpio_get_out_level(1));
+ txPtr = 0;
+ rxPtr = 0;
+ // gpio_put(PIN_DEBUG, !gpio_get_out_level(PIN_DEBUG));
}
- // event_latest = events;
- // if(events & GPIO_IRQ_EDGE_RISE){
- // gpio_put(1, !gpio_get_out_level(1));
- // } else if (events & GPIO_IRQ_EDGE_FALL){
- // // gpio_put(1, !gpio_get_out_level(1));
- // }
}
-
-// void spipi_gpio_raw_handler(void){
-// gpio_put(1, !gpio_get_out_level(1));
-// if(gpio_get_irq_event_mask(PIN_CS) & GPIO_IRQ_EDGE_RISE){
-// gpio_acknowledge_irq(PIN_CS, GPIO_IRQ_EDGE_RISE);
-// gpio_put(1, !gpio_get_out_level(1));
-// }
-// }
+void spipi_irq_handler(void){
+ gpio_put(PIN_DEBUG, !gpio_get_out_level(PIN_DEBUG));
+ // both have up to 8 bytes to read / write per interrupt ?
+ // get bytes while readable,
+ for(uint8_t c = 0; c < 8; c ++){
+ if(spi_is_readable(SPI_INST) && rxPtr < txLen){
+ rxBuffer[rxPtr] = SPI_HW->dr;
+ rxPtr ++;
+ }
+ }
+ // write bytes while writable
+ for(uint8_t c = 0; c < 8; c ++){
+ if(spi_is_writable(SPI_INST) && txPtr < txLen){
+ SPI_HW->dr = txBuffer[txPtr];
+ txPtr ++;
+ }
+ }
+ // rx
+ // if we're out of data, we could turn interrupts off w/ this:
+ // i.e. *just* turning the RX-interrupt on... ??
+ // SPI_HW->imsc = 0 | SPI_IMSC_RXIM_ON;
+}
void spipi_begin(void){
+ // dummy pin
+ gpio_init(PIN_DEBUG);
+ gpio_set_dir(PIN_DEBUG, GPIO_OUT);
+
+ // dummy buffer
+ for(uint8_t i = 0; i < 255; i ++){
+ txBuffer[i] = i;
+ }
+
// uh ?
gpio_init(PIN_CS);
gpio_set_dir(PIN_CS, GPIO_IN);
// let's actually just get the CS LOW/HI interrupt first,
// so we can reset our buffer states (etc)
- // gpio_set_irq_enabled_with_callback(PIN_CS, GPIO_IRQ_EDGE_RISE | GPIO_IRQ_EDGE_FALL, false, &spipi_gpio_irq_handler);
gpio_set_irq_enabled_with_callback(PIN_CS, GPIO_IRQ_EDGE_RISE, true, &spipi_gpio_irq_handler);
// gpio_set_input_hysteresis_enabled(PIN_CS, false);
- // or this simpler handler-thing ?
- // gpio_set_irq_enabled(PIN_CS, GPIO_IRQ_EDGE_RISE, true);
- // gpio_add_raw_irq_handler(PIN_CS, &spipi_gpio_raw_handler);
-
// startup the peripheral ?
- // spi_init(SPI_INST, BITRATE);
- // spi_set_slave(SPI_INST, true);
+ spi_init(SPI_INST, BITRATE);
+ spi_set_slave(SPI_INST, true);
// spi_set_format(SPI_INST, 8, SPI_CPOL_0, SPI_CPHA_0, SPI_MSB_FIRST);
+ // oddity where mode 0b11 allow continuous CS_LOW ?
+ // that's right, folks, we can only do this with 0b11 mode, insane:
+ // see https://github.com/raspberrypi/pico-sdk/issues/88#issuecomment-1402204730
+ // and see RP2040 datasheet at 4.4.3.13 !
+ spi_set_format(SPI_INST, 8, SPI_CPOL_1, SPI_CPHA_1, SPI_MSB_FIRST);
// assign pins to SPI peripheral,
// gpio_set_function(PIN_CS, GPIO_FUNC_SPI);
- // gpio_set_function(PIN_SCK, GPIO_FUNC_SPI);
- // gpio_set_function(PIN_RX, GPIO_FUNC_SPI);
- // gpio_set_function(PIN_TX, GPIO_FUNC_SPI);
+ gpio_set_function(PIN_SCK, GPIO_FUNC_SPI);
+ gpio_set_function(PIN_RX, GPIO_FUNC_SPI);
+ gpio_set_function(PIN_TX, GPIO_FUNC_SPI);
// hook up our (one?) interrupt...
// NOTE: changing SPI_INST requires hard-coded change here
- // irq_set_exclusive_handler(SPI1_IRQ, spipi_irq_handler);
+ SPI_HW->imsc = SPI_IMSC_RXIM_ON | SPI_IMSC_TXIM_ON;
+ irq_set_exclusive_handler(SPI1_IRQ, &spipi_irq_handler);
+ irq_set_enabled(SPI1_IRQ, true);
}
-
-
-// void spipi_irq_handler(void){
-// // both have up to 8 bytes to read / write per interrupt ?
-// // get bytes while readable,
-// if(spi_is_readable(SPI_INST)){
-// uint8_t byte = SPI_HW->dr;
-// }
-// // write bytes while writable
-// if(spi_is_writable(SPI_INST)){
-// SPI_HW->dr = 85;
-// }
-// // if we're out of data, we could turn interrupts off w/ this:
-// // i.e. *just* turning the RX-interrupt on... ??
-// SPI_HW->imsc = 0 | SPI_IMSC_RXIM_ON;
-// }
diff --git a/rpi_spi/code/spi_peripheral_bare/spipi.h b/rpi_spi/code/spi_peripheral_bare/spipi.h
index 6c97915..d941fcb 100644
--- a/rpi_spi/code/spi_peripheral_bare/spipi.h
+++ b/rpi_spi/code/spi_peripheral_bare/spipi.h
@@ -4,6 +4,6 @@
#include <Arduino.h>
void spipi_begin(void);
-uint32_t spipi_get_events(void);
+String spipi_print(void);
#endif
\ No newline at end of file
--
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